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THE  LIBRARY 

OF 

THE  UNIVERSITY 

OF  CALIFORNIA 

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SAN  FRANCISCO 
COUNTY  MEDICAL  SOCIETY 


H'2'-^;\ 


OPHTHALMOSCOPY, 

RETINOSCOPY  and 

REFRACTION 


BY 


W.  A.  FISHER,  M.D.,  F.A.C.S. 

CHICAGO.  ILL. 
U.   S.    A. 


Professor  of  OphthalmoloKv.   Chicago  Eye.   Ear.  Nose  and   Throat 

College: 

Late  Professor,  of  Clinical  Ophthalmology,  University  of  Illinois; 

Late   Surgeon,    Illinois   Charitable   Eye   and   Ear    Infirmary; 

Late    President,    Chicago    Ophthalmological     Society; 

Member,    Illinois    State   Medical    Society; 

Chicago   Medical    Society; 

Chicago  Ophthalmological  Society; 

American  Medical  Association; 

Fellow,    American   College    Surgeons; 

Fellow   of   the   Academy  of  Ophthalmology  and   Oto-Laryngology. 


With   2Jt8   iUui^trations   including  4S  colored 
plates 


Pi(blished    by 

W.  A.  Fisher,  M.D.,  F.A.C.S., 

31    North    State    Street, 

Chicago,   III. 

U.   S.   A. 


Copyright,  August,  1922 

BY 

W.  A.   Fisher 


BiemedicU 
Library 


OPHTHALMOSCOPY, 

RETINOSCOPY  and 

REFRACTION 


C24105 


INTKODLCTIOX 


Ophthalmoscopy  is  generally  considered  as  a 
(hificult  suhject.  It  is  one  that  is  not  taught 
cither  practically  or  successfully  in  medical  col- 
leges, with  the  result  that  scarcely  two  per  cent 
of  practitioners  coming  to  the  autlior  for  post- 
graduate teaching  know  h()^\  to  use  the 
o])ht]ialmoscope. 

In  the  author's  o])ini()n  o])litlialmosco])y  and 
tile  fitting  of  glasses  helong  to  the  general  prac- 
titioner, and  acquirement  of  the  necessary  prac- 
tical and  theoretical  knowledge  is  easy,  interest- 
ing and  within  the  reach  of  all. 

This  book  has  been  written  \\  ith  the  intention 
of  teaching  medical  practitioners  and  students 
the  practical  use  of  the  ophthalmoscope  and 
retinoscope,  with  easy  application  of  methods  of 
study,  to  the  detection  of  diseases  of  the  interior 
of  the  eye,  and  for  the  fitting  of  glasses  when  they 
are  indicated. 

By  mastering  the  methods  here  described  and 
equipping  himself  with  the  necessary  instru- 
ments, there  is  no  reason  why  the  general  practi- 
tioner should  not  prescribe  so  as  to  correct  the 
common  errors  of  refraction  and  become  profi- 
cient in  the  use  of  the  o])hthalmosco])e. 

The  author  desires  to  ex])ress  his  thanks  to 
the  staff  of  the  Chicago  Kye,  Kar,  Xose  and 
Throat  College,  for  valuable  suggestions  and 
especially  to  Dr.  J.  1{.  Hoffman  and  Dr.  O.  B. 
Xugent  in  the  preparation  of  the  chapter  on 
Retinosc()])y  and  to  Dr.  Carl  AVagner  on  the 
fogging  system.  W.  A.  F. 

31  X.  State  St..  Chicao'o. 


CONTENTS 

Chai>tek  Pages 

I.     Ophtlialnioscopy l-'24 

II.     Diseases  of  the  Retina ^25-3H 

III.  Diseases  of  the  Choroid 89-56 

IV.  Diseases  of  the  Optic  Nerve .57-73 

V.     Field    of   Vision:      Indirect    and    Direct 

Ophthalmoscopy 74-96 

VI.     Systematic  Examination  of  Eye 97-109 

VII.     (ilaucoma 1  lO-llo 

\'I1I.     Optical   Principles,   Test    Type,   Lenses, 

Refraction,  and  Cycloplegics 116-1,")9 

IX.     Applied  Refraction,  Astigmatism,   Pres- 
byopia    160-184 

X.     Heterophoria — Muscular  Insufficiency...    185-187 

XI.     Retinoscopy 188-^208 

XII.  Measurement  of  Lenses,  Prescription 
writing.  Transposition,  and  Frame  Fit- 
ting       ^209  ^218 

Index 219-223 


COLORED  PLATES 


Pi.ATK  Deschiptiox                                   1*.\(;k 

I.     Dark  Xonnal  Fundus IS 

11.      Liuht  Xonnal  P\in(lus -2(1 

III.  Myopic  Crescent -2^2 

IV.  Detachment  of  the  Retina -2(1 

V.     Retinitis  Pi<>inentosa 80 

VI.     Retinitis  Pigmentosa  with  oblong  (Hsc iVl 

VII.     Embolism  Central  Retinal  Artery 84 

VIII.     Retinitis  Albuniinurica 86 

IX.      Coloi)oma  of  the  Choroid 40 

X.     Sarcoma  of  the  Choroid 4*2 

XI.      Posterior  Staj)hyloma  with  Choroiditis 44 

XII.      Disseminated  Choroiditis 4(1 

XIII.  Rui)ture  of  the  dioroid 48 

XIV.  Central  Choroiditis .50 

XV.     (Vntral  dioroiditis  (Slight) .n 

XVI.      Injury 54 

XVII.      Cflaucoma  with  Atr()i)hy .58 

XVIII.     Optic  Atroi)hy 00 

XIX.      ()i)a(|ue  Xerve  Fibres ({"2 

XX.      Plain  dioked  Disc (>4 

XXI.      Xeuroretinitis ()(i 

XXII.      Papillitis  Ilaeniorrhagica ()8 

XXIII.  (ilauconia 70 

XXIV.  Haeniorrliagic  (Tlauroma 7-2 

X.  B.— A  duplicate  set  of  Plates  for  use  with   the  Sche- 
matic Eve  is  inserted. 


OPHTHALMOSCOPY 
RETINOSCOPY 

and 
REFRACTION 

CHAP']  KR  I 

Ophthai.moscopy 

A  complete  examination  of  the  eye  cannot  be 
made  withont  a  working'  knowle{l<^'e  of  tlie  opli- 
thalmoscope;  and  diseases  of  the  retina,  choroid, 
and  optic  nerve  cannot  be  nnderstood  nnless  the 
examiner  is  master  of  tliis  inex])ensive  little  in- 
strnment. 

The  author  believes  he  has  made  the  subject 
simple,  interesting,  and  within  easy  reach  of  any 
physician  or  medical  student.  The  student  is 
urged  to  follow  closely  the  method  of  instruc- 
tion, since  he  will  be  expected  to  make  a  good 
()j)hthalmoscopic  examination  of  his  first  ])atient. 

If  the  student  is  expected  to  see  the  details  of 
the  fundi  of  the  first  ])atient  examined,  he  must 
be  taught  the  first  ])rinciples  of  ()])hthalm()sco])y 
on  models.  Medical  men  are  usually  deficient 
in  their  (i])lithalm()sc()])ic  studies  and  it  is  a  hard 
task  to  insti'uct  them  upon  li\iug  sub/jects.  W^ith 
the  method  no\\  to  be  described,  the  student  is 
taught  the  use  of  the  ophthalmoseopr  in  a  sur- 
prisingly sliort  time. 


2  OPHTHALMOSCOPY,    RETINOSCOPY   AND    REFRACTION 

Ophthalmoscopy  is  usually  taught  to  luider- 
graduates  ujDon  the  living  subject  in  small  classes ; 
but  it  is  difficult  to  get  enough  instructors,  who 
can  teach,  to  carry  on  the  work  successfully  in 
this  manner;  and  it  is  practicall}^  impossible  to 
get  the  variety  of  cases  necessary  for  instruction 
at  any  specified  time  even  in  very  large  clinics. 

The  author  will  place  in  the  hands  of  his 
readers,  a  method  of  study  whereby  practically 
all  diseases  of  the  interior  of  the  eye  are  observed 
in  a  model ;  and,  when  these  have  been  mastered, 
the  student  will  be  as  well  prepared  to  examine 
the  interior  of  any  patient's  eye  and  study  the 
picture  as  he  would  that  of  any  external  disease, 
because  they  are  just  as  easily  recognized. 

jNIedical  men  as  a  rule  do  not  profess  to  know 
much  about  the  use  of  the  ophthalmoscope;  and 
the  majority  of  them  believe  it  is  practically  im- 
possible for  them  to  learn  its  use  within  a 
reasonable  time.  This  idea  must  be  abandoned 
before  any  progress  can  be  made. 

]Many  medical  men  believe  that  lesions  found 
in  the  interior  of  the  eye  Avhich  would  come  under 
their  observation  would  be  difficult  to  detect ;  but 
this  also  is  not  true.  ]Many  lesions  found  in 
diseases  of  the  retina,  choroid,  and  optic  nerve 
are  usually  so  pronounced  in  ty])e  that  a  diag- 
nosis can  be  made  on  sight.  It  is  the  object  of 
this  chapter  to  sliow  liow  they  can  easily  be  made 
visible. 

Before  beginning  the  subject  of  ophthalmo- 
scopy, a  description  of  the  ophthalmoscope  will 
be  given:  and,  after  that,  the  student  will  be 


Ol'HTFIALMOSCOPY 


Fig.    1 
Electrical     Ophthalmoscope. 


P%.     2. 
Lorintr    Ophthalmoscope. 


expected  to  uiulerstaiul  the  siil)ject  as  he  pro- 
gresses, and  not  pass  anything  until  lie  is  master 
of  it. 

The  OiMrniAi..Ai()sc()PK:  In  the  diagnosis  of 
many  diseases,  including  some  conditions  in  the 
domain  of  ge?iera]  medicine,  which  ])ro(luce  char- 
acteristic clianges  in  the  interior  of  the  eye,  tlie 
use  of  the  ophthalmoscope,  which  is  an  instru- 
ment designed  for  the  illumination  of  its  trans- 
parent media  and  deeper  structures  making  their 
examination  as  sim])le  and  easy  as  that  of  the 
external  ])ortion,  is  indispensable. 


I  OPHTHALMOSCOPY.    RETINOSCOPY    AND    REFRACTION 

There  are  many  models  of  the  instrument,  but 
any  one  whicli  the  doctor  accustoms  himself  to 
is  usually  satisfactory. 

Electrical  Ophthalmoscope:  It  is  easier 
for  a  beginner  to  ilhuninate  the  interior  of  the 
eye  with  an  electrical  ophtlialmoscope,    ( Figure 

1 )  which  while  expensive,  offers  some  advantages. 
The  instrument  most  generally  adopted  in  the 

United  States  of  America  is  the  Loring  ( Figure 

2)  ;  and,  in  tliis  work,  it  will  l)e  described  and 
directions  given  foi*  its  use  in  the  practice  with 
the  model. 

LoRiXG  Oph'J'halmoscope:  The  essential 
parts  of  a  Loring  ()])hthalmoscope  are  a  per- 
forated mirror  for  reflecting  the  light  into  the 
eye  and  two  discs  carrying  convex  ( -p)  and  con- 
cave ( — )  lenses. 

The  larger  inner  disc  contains  seven  convex 
lenses,  varying  by  diff'erences  of  1  dio])tre  (abbre- 
^iated  D)  from  1  to  7  dioptres,  and  eight 
concave  ones  varying  similarly  from  1  to  8  diop- 
tres. Between  the  plus  and  minus  1  D.  lenses 
in  this  disc  is  left  an  opening  of  corresponding 
size  which  contains  no  lens  and  is  s])oken  of  as  the 
aperture.  Witli  these  may  be  combined  the 
lenses  in  the  small  outer  disc  wliich  contains  one 
each  of  H-  0..50  D.  and  +  16  D..  as  Avell  as  — 
0.50  D.  and  —  16  D.  lenses.  By  combining  the 
outer  and  inner  discs,  one  is  able  to  get  any  con- 
vex or  concave  lens  from  0..50  to  24  D. 

The  unit  of  lens  measure,  the  dioptre,  men- 
tioned above  and  frequently  used  throughout  the 
text,   has   liv   international    am-eement   been   ac- 


OPHTHALMOSCOPY  D 

cepted  as  the  strength  of  that  lens  whieh  has  its 
focus  at  a  (hstance  of  one  metre  (40  inches). 
With  the  dioptric  strength  of  a  lens  known,  its 
focal  length  is  ascertained  hy  (hvision  into  100 
centimeters  or  4-0  inches,  and  conversely  the 
(hoptric  measurement  is  arrived  at  l)y  division 
of  the  focal  (hstance  into  these  same  figures. 
Thus  a  lens  of  2  1).  has  a  focal  length  of  .30 
centimeters,  or  20  inches;  and  one  of  2.5  centi- 
meters or  10  inch  focal  length  is  sj)oken  of  as  a 
4  1).  lens  eithei*  plus  or  minus,  as  the  case  may  he. 

The  fundus  of  a  normal  eye  can  he  seen 
through  the  aperture  without  any  lens;  hut,  if 
the  eye  examined  is  hypermetropic  (far  sighted), 
plus  lenses  are  required;  if  myopic  (near  sighted) 
minus  lenses  are  necessary  to  secure  a  correct 
view  of  it. 

It  is  not  necessary  to  have  absolute  darkness 
for  ophthalmoscopy,  but  the  darker  the  examin- 
ing room,  the  better  the  illumination  of  the 
fundus  and  consequent  ease  of  examination  and 
accuracy  of  findings.  In  the  sick  room,  drawing 
the  shades  will  sufHce;  hut  in  the  office,  the  walls 
and  ceilings  may  well  be  ])ainted  black. 

Direct  ^iF/riioi):  To  examine  an  eye  witli 
the  ophthalmoscope  by  direct  method,  the  ex- 
aminer should  be  as  near  it  as  possible,  keep  both 
eyes  open,  and  look  into  the  distance  with  the 
examining  eye  through  the  a])erature  of  the  in- 
strument, l^y  doing  so,  he  will  learn  to  relax 
his  own  accommodation. 

Light:  The  interior  of  the  eye  must  be  illu- 
minated and  students  find  it  difficult  at  first  to 


OPHTHALMOSCOPY,    RETINOSCOPY   AND    REFRACTION 


Fig.   3.      Spool 


reflect  and  keep  the  light  directed  into  the  eye 
while  making  an  examination.  By  practice,  how- 
ever, this  can  he  learned  upon  the  model  as  readily 
as  one  can  hy  practice  learn  to  shoot  pigeons 
thrown  from  a  trap. 

Illumination  :  The  simplest  inexpensive 
method  of  mastering  control  of  the  illumination 
for  the  application  of  ophthalmoscopy  is  to  prac- 
tice reflecting  the  light  from  the  ophthalmoscope 
into  an  ordinary  spool  ( Figure  3 )  with  the  end 
toward  the  operator  open  and  the  other  closed 
with  white  paper  upon  the  inside  of  whicli  have 
heen  placed  hlack  or  red  markings  that  can  be 
identified  by  tlie  student  as  he  looks  through  the 
aperture  of  the  instrument.  After  the  student 
has  learned  to  control  the  reflected  liglit  and  is 
able  to  see  through  the  perforation  in  the  mirror, 
it  is  not  difficult  to  illuminate  the  interior  of  the 
eye.  The  colored  pictures  that  follow  can  be 
studied  in  the  book  and  a  working  knowledge 
obtained,  but  a  much  better  method  is  to  studv 


OPHTHALMOSCOPY 


Fig.   4.      Author's    Practical   Schematic    Eye 


the  pictures  in  a  special  adopted  model  for  the 
purpose. 

A  Practical  SchemxVtic  Eye:  (Fig.  4) 
can  be  made  by  any  carpenter  in  the  following 
manner.  Select  a  piece  of  wood,  round  or  square, 
3I/8  inches  long  and  21/1^  inches  in  diameter:  bore 
a  hole  1-^4  inclies  in  diameter  through  it,  and  saw 
a  slit  through  the  barrel  near  one  end  to  insert 
the  picture,  and  anotlier  slit  at  the  ()])])osite 
end,  large  enough  to  insert  a  phis  18.00  1).  lens 
from  the  opthahiioscopic  case.  The  two  slits 
should  be  two  inches  a])art  in  order  to  a])proxi- 
mate  a  normal  eye.  Two  tacks,  (one  on  eitlier 
side)  are  driven  into  tlie  front  end  with  the  heads 
])roiecting  far  enougli  to  liold  tlic  lenses  from  the 
trial  case,  to  be  used  for  retinoscopy.     Degrees 


6  OPPITHALMOSCOPY,    RETINOSCOPY    AND    REFRACTION 

denoting  tlie  axis  of  the  cylinder  can  be  marked 
on  the  model  as  they  are  made  on  any  trial  frame. 
A  stand  can  be  made  by  making  a  base  and  an 
upriglit  and  joining  the  ])ase  with  the  model,  in- 
sei'ting  one  end  in  a  hole  made  in  the  barrel,  the 
other  in  the  base.  The  model  can  be  ])ainted  as 
desired,  but  the  inside  of  tlie  barrel  should  ])e 
black;  the  stand  should  be  made  to  give  tlie  model 
an  incline  of  about  30  degrees. 

A  picture  is  placed  in  the  back  of  the  barrel, 
and  in  front  a  plus  13  dioptre  glass  from  the 
ophtlialmoscopic  case.  In  front  of  this  lens  is 
])asted  a  piece  of  black  paper  or  cardboard  witli 
a  1.5  millimeter  opening  in  the  center  to  represent 
the  pupil.  When  proficiency  is  obtained  witli 
the  large  pupil,  another  paper  is  pasted  over  tlie 
first  one  with  a  10  millimeter  opening  and  wlieii 
tlie  picture  is  easily  seen,  another  pa])er  can  be 
pasted  over  the  last  one  with  a  .5  millimeter  open- 
ing in  the  center  of  it.  The  pictures  in  the  back  of 
the  model  can  be  studied  with  the  ophthalmo- 
scope, using  any  desired  pupil  until  proficiency 
is  obtained. 

To  make  ophthalmoscopy  simple,  easy,  and 
interesting,  one  should  master  the  model  before 
looking  at  the  eye  of  a  ])atient.  Retinosco])y 
can  be  ])racticed  upon  the  model  with  a  10  milli- 
meter pupil,  various  strength  lenses  being  placed 
in  front  of  the  pupil.  Du])licates  of  the  24  pic- 
tures are  ])laced  in  tlie  book  to  be  cut  out. 
mounted  on  cardboard,  with  projecting  thumb 
piece  for  inserting:  these  are  for  use  with  the 
model. 


OPHTHALMOSCOPY 


Fig. 


Author's     Schema; 


Eye. 


The  author's  Schematic  eye  (Fit^'ure  .3)  is  a 
model  designed  to  make  the  study  of  ophthahno- 
sco])y  simple,  easy  and  interesting.  It  consists 
of  one  cylindrical  tuhe  telesco])ing  another  one 
in  such  a  manner  that  a  long  or  short  eye  can 
he  produced.  If  the  t\\'()  ])arrels  arc  ])us]ied  to- 
gether as  far  as  jjossihlc  we  have  a  hypermetro])ic. 
short,  or  far  sighted  eye.  If  the  two  harrels  are 
pulled  apart  as  t'ai'  as  possihle.  we  ])roduce  a 
myopic,  long,  oi*  near  sighted  eye.  If  half  way. 
— normal. 


10       OPHTHALMOSCOPY,    RETINOSCOPY   AND    REFRACTION 

The  model  has  a  lens  to  represent  the  crystal- 
line lens  of  the  human  eye,  and  an  iris  diaphragm. 
This  iris  diaphragm  which  when  fully  dilated 
produces  a  pupil  of  30  millimeters,  is  made  to 
open  and  close  at  the  will  of  the  operator  and 
can  be  made  to  represent  a  normal,  contracted, 
or  dilated  pupil.  The  beginner  can  commence  his 
study  with  the  maximum  pupil  and  gradually 
decrease  the  size  until  it  is  much  smaller  than 
the  pupil  of  a  normal  eye. 

When  the  student  has  mastered  control  of  the 
light  and  can  examine  the  fundus  of  the  schematic 
eye  which  is  provided  with  twenty-four  pictures, 
two  normal  and  twenty-two  abnormal  ones,  rep- 
resenting gross  pathological  lesions,  he  is  ready 
to  successfully  examine  the  human  eye. 

EXAMIXATIOX  OF  THE  SCHEMATIC  Eye:      The 

direct  examination  of  the  schematic  eye  should 
be  mastered  before  the  student  attempts  the  ex- 
amination of  a  patient.  If  this  be  done  and  well 
done,  he  should  be  able  to  make  a  good  ophthal- 
mosco23ic  examination  on  the  first  patient  seen. 

To  be  a  master  of  the  schematic  eye  one  should 
not  onh^  be  able  to  distinctly  see  the  fundus,  but 
to  know  what  to  look  for  and  recognize  it  when 
found  as  well.  In  the  study  of  the  individual 
pictures,  the  student  should  bear  in  mind  that 
no  great  attention  should  be  given  to  the  color 
of  the  background  of  the  eye,  as  this  differs  in 
a  hundred  cases,  as  one  hundred  faces  differ. 

The  student  should  also  understand  that  these 
twenty-four  pictures  were  made  to  teach  and 
impress  the  pathological  lesions  as  well  as  the 


OPHTHALMOSCOPY  11 

normal  fuiuliis  on  his  mind.  All  of  them  were 
made  to  first  represent  normal  fundi  and  are  as 
different  in  color  as  three  colors  can  make  possi- 
ble. After  the  twenty-four  normal  ])ictures  were 
finished,  twenty-two  of  them  were  made  ])ath- 
ological  hut  the  normal  ])art  of  the  ])ieture  re- 
mains. 

Xerye  Head:  The  nerve  head  should  he 
noted,  hut  in  actual  ])ractice  much  stress  should 
not  he  ])laced  u|)on  its  color.  It  frequently  has 
a  ^vhite  scleral  and  black  choroidal  rino^,  which 
are  normal  and  should  be  in  the  same  plane  as 
other  parts  of  the  fundus,  not  too  high,  "swollen 
nerve"  or  "choked  disc"  (Page  Qo)  nor  pushed 
back  "cupped"  as  in  glaucoma  (Page  71). 

XoR:\rAL  Eyes:  In  normal  eyes  the  vessels 
should  emerge  from  the  center  of  the  nerve  and 
not  from  the  edge  ( Page  19 ) .  If  they  all  emerge 
from  the  edge  of  the  nerve,  a  picture  of  glaucoma 
is  seen  ( Page  71 ) .  If  some  of  the  arteries  emerge 
from  the  center  of  the  nerve  and  some  from  the 
edge,  there  is  a  possibility  of  atro])hy  and  the  field 
should  be  taken. 

The  Retixa:  The  retina  is  transparent  and 
we  need  to  observe  its  vessels  only.  The  arteries 
are  smaller  than  the  veins,  which  accompany  the 
former  rather  closely,  the  ratio  of  size  being  as 
two  is  to  three.  These  vessels  have  no  regular 
course  and  slight  deviations  should  not  be 
noted.  By  referring  to  the  twenty-four  pictures 
which  follow,  it  will  be  seen  that  in  no  two  are 
the  retinal  vessels  the  same. 

Working  Pean  :    Before  beginning  the  study 


J  2       OPHTHALMOSCOPY,    RETINOSCOPY    AND    REFRACTION 

of  the  individual  pictures  a  general  working  plan 
of  using  the  ophthalmoscope  should  be  adopted. 
The  student  must  be  able  to  determine  whether 
an  eye  is  hypermetro])ic  or  mj^opic  before  he  can 
detect  gross  pathological  lesions. 

Working  with  the  schematic  eye,  one  should 
measure  refraction  by  the  image  of  the  screen — 
the  stippling  seen  in  the  picture.  When  colored 
pictures  are  printed,  a  screen  is  used;  and,  when 
we  magnify  these  pictures  with  the  ophthalmo- 
scope, its  image  is  easily  seen.  In  fact  one  can- 
not help  seeing  it  and  this  image  is  observed  in 
the  measurement  of  the  refraction  instead  of  the 
white  lines  on  tlie  arteries  in  the  human  eye. 

TWO  RULES  TO  REMEMBER 

First — Hypermetropia:  The  strongest  con- 
vex ( + )  lens  with  Avhich  the  screen  can  be  seen 
at  all  represents  the  measure  of  the  hyper- 
metropic, "far  sighted"  "short  eye"  produced 
when  the  barrels  of  the  schematic  eye  are  fully 
closed. 

Second — JNIyopia:  In  myopia  "near  sighted" 
or  "long  eye"  is  produced  when  the  barrels  of 
the  model  are  separated  beyond  the  point  marked 
normal  (the  more  the  separation  the  higher  de- 
gree of  myopia)  ;  the  weakest  minus  ( — )  lens 
with  which  the  screen  can  be  seen  at  all  will  be 
the  measure  of  the  myopia,  short  sighted,  or 
long  eye. 

When  the  student  can  readily  measure  the 
myopia  or  hypermetropia  in  the  schematic  eye, 


OPHTHALMOSCOl'^  13 

set  at  any  one  of  the  numerous  ])ossible  positions, 
he  will  i-eadily  nieasui'e  the  ret'raetive  error  in 
the  human  eye. 

Position  or  'ihk  Kxaminkk  and  the  Model: 
Tlie  model  should  he  plaeed  on  a  table  high 
enough  to  he  on  a  level  with  the  examinei-\ 
eye  when  sitting  in  an  easy  ])osition,  in  iVont  of 
it.  When  using  the  right  eye,  sit  in  front  of  and 
to  the  right  side  of  the  model  and  ])laee  the  light 
to  its  right  side.  When  using  the  left  eye,  sit 
in  front  of  the  model  to  the  left  and  have  the  light 
on  the  left  side  of  the  model.  These  are  the  posi- 
tions one  would  assume  if  a  ])atient  was  being 
examined.     (  See  Page  97. ) 

Source  of  I^i(;ht:  The  source  of  light  may 
be  either  an  oil  lam]),  gas,  or  electric  light  with 
a  frosted  globe,  and  should  be  on  a  level  with  the 
model.  The  h'ght  should  be  ])laced  upon  a  brac- 
ket that  can  be  moved  to  either  side  of  the  model 
as  the  student  works  with  his  right  or  left  eye,  and 
which  can  be  moved  u])  or  down  in  order  to  get 
the  desired  light. 

Size  of  Pimml  ix  the  Schemaik-  Kve:  The 
pupil  in  the  schematic  eye  can  be  made  so  wide 
that  anx'one  can  see  the  ])icture  in  the  back  of 
the  model  the  first  time  it  is  examined:  the 
pu])il  can  be  reduced  gi-adually  as  ])r()ticiency  is 
accjuired. 

Distance  From  the  Model:  Wh.en  looking 
into  a  room  through  a  key-hole,  the  closer  the 
observer  is  to  it  the  larger  will  be  the  field.  The 
same  is  true  in  lookinu'  into  the  model,  or  into 


14       OPHTHALMOSCOPY,    RETINOSCOPY   AND   REFRACTION 

the  eye;  the  closer  the  observer,  the  more  he  will 
see. 

Direct  Exa3iixation  :  With  the  room  suf- 
ficiently darkened,  the  source  of  light  and  the 
model  properly  arranged,  begin  the  examination 
by  assuming  the  first  position  for  direct  o])hthal- 
moscopy  (Page  97),  at  a  distance  of  about  two 
feet ;  and,  with  the  mirror  of  the  ophthalmoscope 
tilted  towards  the  source  of  light,  reflect  it  into 
the  pupil  of  the  model,  which  at  first  should  be 
made  as  large  as  possible;  when  the  red  reflex 
is  seen  through  the  a])ertin*e  of  the  instrument 
gradually  approach  it  coming  as  close  as  possible 
and  assume  the  second  position  for  direct  ophthal- 
moscopy. The  same  position  should  be  observed 
as  when  examining  a  patient.     (See  Page  97.) 

What  to  Forget:  To  make  ophthalmoscopy 
simple  and  easy,  the  observer  must  first  know 
what  constitutes  the  normal  eye.  Forget  the 
general  color  of  the  picture  examined  because  the 
fundi  of  no  two  eyes  are  alike.  They  are  as 
different  as  the  faces  seen  on  a  crowded  street; 
they  all  have  eyes,  ears,  nose  and  mouth,  but  these 
all  go  together  to  make  the  face. 

All  fundi  have  a  nerve  head,  and  retinal  vessels, 
but  the  color  of  the  former  varies  so  much  that 
the  observer  should  forget  about  its  having  a 
color  as  well  as  the  color  of  the  general  back- 
ground of  the  eye  because  of  its  variations. 

Text  books  on  ophthalmology  usually  devote 
so  much  space  to  describing  the  color  of  the  back- 
ground of  the  eye  that  the  student  soon  becomes 


OPHTHALMOSCOPY  15 

confused.  In  this  method,  students  are  not  ex- 
pected to  know  or  remember  anything  about  the 
color  of  the  fundus. 

Things  to  Remember  :  The  student  must  be 
able  to  measure  the  refraction  of  the  eye  before 
he  can  make  progress  in  diagnosis.  The  observer 
always  begins  his  direct  ophthalmoscopic  exam- 
ination with  tile  aperture,  when  he  will  be  able 
to  see  the  screen  in  normal  and  liypermetropic 
eyes. 

Screen:  If  the  observer  can  see  the  screen 
with  the  aperture  he  will  rotate  convex  ( + ) 
lenses  in  front  of  it  by  turning  the  wheel  on  the 
edge  and  will  remember  that  tlie  strongest  convex 
lens  with  which  he  can  see  the  screen  ai  all  will 
represent  the  amount  of  hypermetropia.  If  he 
cannot  see  the  screen  with  the  aperture  of  the 
ophthalmosco])e  he  must  turn  on  minus  lenses  to 
make  it  visible;  the  weakest  minus  glass  with 
^\  hich  he  can  see  the  screen  represents  the  myopia. 

Retinae  Vessei-s  :  The  student  must  remem- 
ber that  the  retinal  veins  are  one  third  larger 
than  the  arteries  and  that  tlie  retinal  vessels  seem 
to  come  out  of  the  center  of  the  optic  nerve  and 
course  across  the  fundus. 

Scleral  and  Choroidal  Rixcjs:  There  may 
be  a  white  scleral  ring  that  the  student  can  see 
around  the  edge  of  the  nerve  and  a  black  choroi- 
dal ring  on  the  outside  of  it.  These  two  rings 
may  vary  or  may  not  be  visible  and  they  some- 
times appear  to  encircle  the  nerve  head  or  only 
part  of  it;  but  \}\  no  case  are  they  ])athological. 


16       OPHTHALMOSCOPY,    RETINOSCOPY    AND    REFRACTION 

Atkophu  and  Pigment  Spots:  If  atrophic 
or  pigmented  areas  can  be  seen  that  are  nearer 
to  the  observer  than  the  retinal  arteries,  these 
spots  are  situated  in  tlie  retina.  If  tlie  spots, 
either  light  or  dark,  are  farther  away  from  the 
observer  than  the  retinal  vessels;  in  other  words, 
if  the  retinal  vessels  run  over  the  spots,  they  are 
in  the  choroid.  Remembering  the  things  to  be 
remembered  and  forgetting  the  things  that  are  to 
be  forgotten,  the  individual  pictures  will  now  be 
observed  in  the  schematic  eye;  but  before  doing 
this,  the  student  will  be  especially  cautioned  to 
remember  two  rules. 

First,  the  strongest  plus  lens  zcith  tchieh  he 
can  see  the  screen  in  the  model  measures  the 
hifpermetrojJUL 

Second,  the  zceakest  minus  lens  zcith  zchich  Ju 
can  see  the  screen  measures  the  mi/opia. 

It  is  very  important  to  remember  these  tzco 
rules. 

It  will  be  natural  for  the  observer  to  put  on 
glasses  with  which  he  can  see  the  screen  best, 
but  that  would  be  wrong.  The  strongest  convex 
( -\-)  or  weakest  concave  ( — )  lens  with  whicli 
he  can  see  the  screen  at  all  is  the  correct  one. 

Ophthalmoscopy  must  be  mastered  before 
much  progress  can  be  made  in  the  study  of  opli- 
thalmology,  and  the  student  is  urged  to  study  the 
following  pictures  very  carefully.  They  can  be 
studied  without  a  model  but  the  use  of  this  device 
simplifies  the  subject,  develops  skill,  and  makes 
oplithalmosco]:)y  simple,  easy,  and  interesting. 


18       OPHTHALMOSCOPY,    RETINOSCOPY   AND    REFRACTION 


Dark   Normal   Fundus 

Plate  I. 


OPHTHALMOSCOPY  19 

XoKMAL  Dark  Fundus:  Plate  1  represents 
a  (lark  normal  fundus.  The  lif^ht  streaks  that 
would  be  found  in  the  human  (retinal)  arteries, 
are  absent  as  they  are  in  all  the  following  pic- 
tures. Otherwise  it  is  a  true  reproduction  of  a 
dark  normal  fundus. 

Retinal  Vessels:  The  retinal  vessels  are 
seen  emerging  from  the  center  of  the  optic  nerve 
and  passing  across  the  fundus  in  a  normal  man- 
ner, ihe  veins  being  one-third  larger  than  the 
arteries. 

The  Nerve  Head:  The  nerve  head  appears 
slis^htly  hvperaemic  but  its  color  and  also  the 
color  of  the  whole  fundus  should  be  overlooked, 
because  it  has  been  emphasized  that  the  student 
in  his  early  studies  should  ignore  the  color  of  the 
fundus  and  optic  nerve. 

\'\nien  the  moimted  copy  of  the  above  plate 
is  studied  in  the  model  adjusted  to  make  it  either 
normal  or  hypermetropic,  "short''  the  screen  will 
be  seen  when  it  is  observed  through  the  aperture 
of  the  ophthalmoscope.  Plus  (  +  )  lenses  sliould 
be  turned  before  the  aperture  of  the  ophthalmo- 
scope as  long  as  the  screen  can  be  seen  and  the 
strongest  one  with  which  this  can  be  done  will 
register  the  amount  of  hypermetronia.  The 
model  can  then  be  made  lono\  "mvopic"  and  the 
weakest  minus  ( — )  lens  with  which  he  can  see 
the  screen,  will  record  the  amount  of  myopia. 

AM  of  the  following  plates  should  be  studied 
in  this  manner  in  order  to  obtain  practice  in 
measuring  refraction  because  the  eve  must  be  re- 
fracted before  anv  diagnosis  can  be  made. 


20       OPHTHALMOSCOPY,    RETINOSCOPY    AND    REFRACTION 


Light  Normal  Fundus 

Plate  II. 


OPHTHALMOSCOPY  21 

Normal  Light  Fundus  :  Plate  11  represents 
a  normal  light  fundus  with  the  retinal  vessels 
emerging  from  the  center  of  the  optic  nerve  and 
coursing  across  the  fundus  in  a  normal  manner. 

Xerm^:  Hp:au:  The  nerve  appears  to  have  the 
same  color  as  the  fundus  with  a  light  spot  in  its 
center,  the  scleral  ring  extends  half  way  around 
the  nerve  head  on  the  nasal  side,  and  the  choroidal 
ring  extends  nearly  half  way  around  the  nerve 
head  on  the  temporal. 

Choroidal  and  Scleral  Rings:  The  choroi- 
dal and  scleral  rings  may  be  absent  or  much  more 
marked  in  normal  eyes,  but  they  sliould  also  be 
ignored  when  looking  for  pathological  lesions. 

XoRMAL  Findings  :  In  this  picture  as  well  as 
Plate  1,  the  student's  attention  is  called  to  normal 
findings.  The  general  background  may  vary 
from  the  lightest  to  the  darkest  and  yet  the  eye 
remain  normal. 

This  picture  should  be  studied  in  the  model  in 
the  manner  described  in  the  discussion  of  Plate  I. 


Fig.    6.     Noi-mal    cross    secti 


Normal  Cross  Section  :  Figure  6  represents 
a  cross  section  of  Plate  11.  The  student  will 
notice  that  there  are  no  elevations  or  excavations 
at  the  nerve  head,  or  in  any  part  of  the  fundus. 


22       OPHTHALMOSCOPY,    RETINOSCOPY    AND    REFRACTION 


Myopic  Crescent 

Plate  III. 


OPHTHALMOSCOPY  23 


Myopic  Ckkscext:  Plate  III.  The  retinal 
\essels  are  normal  and  tlie  ehoroidal  vessels, 
broader  than  those  of  the  retina,  show  through 
the  latter  and  there  is  a  large  Avliite  crescent  on 
the  temporal  side  of  the  nerve  head.  When  such 
a  pictiu'e  is  found  in  a  myopic  oa*J.ong  e^^e,  a  diag- 
nosis of  mj^opic  crescent  is  made.  Save  for  the 
large  crescent  at  the  side  of  the  optic  nerve,  the 
picture  is  normal.  In  low  degrees  of  myo])ia,  the 
fundus  often  presents  a  normal  appearance;  but 
the  above  is  very  fre(]uently  found  in  high  de- 
grees. 

Diseases  of  ]Myopia:  The  student  is  re- 
minded that  a  variety  of  lesions  may  be  found 
in  high  degrees  of  myopia,  (near  sighted  eyes) 
such  as  choroiditis,  uveitis,  detachment  of  the  ret- 
ina, dislocated  lens,  and  even  general  destruction 
of  the  eye  ball. 


CHAPTER  II 

Diseases  of  the  Retina:  The  five  colored 
plates  that  follow  represent  the  commoner  dis- 
eases of  the  retina,  and  they  should  l)e  carefully 
studied  with  the  ophthalmoscope  in  the  model. 
The  model  should  he  made  short,  "hypermetro- 
pic" and  the  refraction  carefully  measured,  then 
long,  "myopic"  and  the  refraction  again  meas- 
ured. This  should  he  done  in  order  to  acquire 
an  idea  of  elevations  and  excavations,  which  must 
be  done  in  order  that  a  diagnosis  can  be  made. 
This  exercise  will  be  found  to  be  quite  satisfac- 
tory upon  the  model. 

It  is  the  intention  of  the  author  to  give  the 
student  and  practitioner  a  working  knowledge 
of  ophthalmoscopy  and  describe  a  few  pictures 
of  lesions  usually  found  in  the  fundus;  the  rare 
ones  are  not  mentioned. 

If  the  following  pictures  are  carefully  studied 
in  conjunction  with  the  use  of  the  model,  the 
student  will  be  well  prepared  to  make  diagnosis 
of  diseases  of  the  fundus  as  he  Avill  meet  them. 

A  beginner  in  tlie  study  of  diseases  of  the  eye 
is  usually  early  in  forming  ideas  regarding  dis- 
eases of  the  fundus ;  he  begins  as  a  rule  by  imag- 
ining diseases  that  are  next  to  impossible.  If 
the  normal  eye  and  gross  lesions  are  well  under- 
stood, the  lesser  lesions  soon  become  simple.  A 
greater  number  of  diseases  of  the  retina  would 
only  have  a  tendency  to  complicate  tlie  subject. 


26       OPHTHALMOSCOPY,    RETINOSCOPY   AND    REFRACTION 


Detachment    of    Retins 

Plate  IV. 


DISEASES    OF    THE    RETINA  27 

Detach:ment  of  the  Retina:  Plate  IV. 
There  is  a  large  white  crescent  extending  more 
than  half  around  the  nerve  head  ( Posterior  stap- 
hyloma). The  upper  part  of  the  fundus  is  red 
and  the  lower  part  is  of  a  lighter  color  and  is  in 
folds. 

The  upper  ])art  a])pears  red  I)ecause  of  the 
choroid  immediately  under  the  retina  wliile  the 
lower  part  is  of  a  lighter  color,  hecause  the 
choroid  cannot  he  seen,  as  the  result  of  there  heing 
something  hetween  it  and  the  retina.  The  retinal 
vessels  pass  over  the  entire  fundus  hut  the  stu- 
dent will  notice  tliat  they  seem  to  he  hroken  at  the 
edge  of  the  detachment,  or  at  the  junction  of  the 
light  and  red  areas.  A  similar  picture  is  seen 
in  sarcoma  of  the  choroid,  but  a  striking  differ- 
ence is  seen  when  comparing  the  retinal  vessels 
of  detachment  with  those  of  sarcoma.  ( See  Plate 
X.) 

A  break  will  be  observed  at  each  told  ot  the 
retina  in  detachment,  while  in  a  sarcoma,  breaks 
will  be  seen  only  at  the  junction  of  the  light  and 
red  areas  because  of  the  absence  of  folds  in  the 
latter. 

Tension  :  In  detachment  of  the  retina  the  eye 
is  usually  below  normal. 

Hyper:\ietropia:  In  both  detachment  of  the 
retina  and  sarcoma,  the  affected  areas  are  more 
hypermetropic  than  the  normal  part  of  the  fun- 
dus. If  unable  to  make  a  differential  diagnosis 
between  the  two  conditions  by  the  a])])earance  of 
the  involved  retinal  vessels,  the  doubt  can  usually 
be  easily  cleared  u])  by  puncture  of  the  sclera 


28       OPHTHALMOSCOPY,    RETINOSCOPY    AND    REFRACTION 

over  the  affected  portion  after  cocainizing  the  eye. 
If  the  lesion  proves  to  be  a  detachment,  fluid  will 
escape  and  the  retina  will  be  temporarily  replaced 
in  position  as  can  be  determined  with  the  ophthal- 
moscope. Should  it  be  sarcoma,  there  will  be  no 
change  in  position  or  size  of  the  tumor. 


Fig.  7.     Detachment  of  Retina.     Cross  section  Plate  IV 

Figure  7  represents  a  cross  section  of  Plate 
IV.  The  student  will  note  the  elevation  or  hy- 
permetropia  of  the  detached  portion.  If  the  re- 
fraction is  made  with  the  ophthalmoscope  at  (A) 
and  then  at  (B)  without  removing  the  ophthal- 
moscope from  the  eye,  the  difference  in  the  re- 
fraction will  be  easily  measured. 

Elevation:  When  measuring  the  refraction 
of  two  portions  of  the  fundus,  a  refractive  differ- 
ence of  3  D.  is  equivalent  to  a  difference  of  1 
millimeter  in  level.  The  student  will  shortly 
become  adept  at  estimating  the  height  of  any 
elevations  or  depth  of  any  depressions  he  may 
meet. 

Prognosis  :    Usually  blindness. 

Treatment:  Rest  in  bed,  laxative,  sweats, 
potassium  iodide,  sub-con junctival  injections  of  1 
to  3%  salt  solution  or  5%  citrate  of  soda;  draw 


DISEASES    OF    THE    RETINA  29 

off  fluid  by  puncture  or  trephine  the  sclera  after 
laying  back  the  conjunctiva  and  exposing  it, 
after  which  the  opening  is  closed  with  one  or  two 
sutures. 


30       OPHTHALMOSCOPY,    RETINOSCOPY    AND    REFRACTION 


Retinitis    Pigmentosa 

Plate  V. 


Retinitis  Pig:\ientosa:  Plate  V.  The  reti- 
nal vessels  are  normal  and  the  scleral  and  choroi- 
dal rings  are  plainly  visible.  The  background 
of  the  fundus  is  dark,  spots  of  pigment  are 
noticed,  which  are  seen  to  be  deposited  on  the 
retinal  vessels.  When  the  fundus  is  examined 
with  the  ophthalmoscope,  the  retinal  vessels  dis- 
appear first,  when  plus  glasses  are  used,  showing 
clearly  that  the  spots  are  in  the  retina.T) 


DISEASES    OF    THE    RETINA 


31 


There  is  no  difference  in  the  ophthalmoscopic 
pictures  of  retinitis  pigmentosa  and  ac(|uired 
syphihs;  but  the  former  always  appears  in  child- 
hood showing  itself  symptomatically  by  com- 
plaint of  the  early  onset  of  darkness  toward  the 
close  of  the  day,  even  long  before  normal  individ- 
uals note  any  failure  of  the  illumination.  This 
symptom  alone  occurring  in  a  child  is  sufficient 
for  a  positive  diagnosis  of  retinitis  pigmentosa 
without  the  ophthalmoscopic  picture.  External 
examination  does  not  reveal  any  symptom  of 
disease. 

Figure  8  represents  a  cross 
section  of  Plate  V.  The 
student  will  note  that  the  pig- 
mented spots  are  in  front  of 
the  retinal  vessels  and  can 
easily  be  distinguished  from 
choridal  pigment  by  meas- 
urement of  the  refraction  of 
one  or  more  of  the  s])ots  and  of  an  adjacent  nor- 
mal area  ^vith  the  o])hthalmoscope  as  described 
on  Plate  IV. 

PiKKiXOSis:  Blindness  usually  occurs  about 
middle  life  or  a  little  later. 

Treatment  :  No  treatment  has  as  yet  been 
found  to  be  of  benefit.  However,  errors  of  re- 
fraction should  be  corrected. 


Fig.    8 
Retinitis  Pigmen- 
tosa.    Cross   Section 
Plate  V. 


32       OPHTHALMOSCOPY,    RETINOSCOPY   AND   REFRACTION 

Retinitis  Pigmentosa  with  Oblong  Disc 
(Luetic  Retinitis)  :  Plate  VI.  This  picture  is 
produced  in  acquired  syphilis;  occurring  only  in 
adults  and  closely  resembles  retinitis  pigmentosa. 

The  spots  of  pigment  are  plainly  in  front  of 
the  retinal  vessels;  whereas,  if  thc}^  were  in  the 
choroid,  the  vessels  would  be  anterior  to  the  spots. 


Retinitis  Pigmentosa  with  Oblong  Disc. 

Plate  VI. 


In  observing  the  pictures  in  the  model,  the  spots 
will  be  seen  after  the  arteries  have  disappeared 
when  plus  lenses  are  introduced  into  the  aper- 
ture of  the  ophthalmoscope,  thus  showing  the 
spots  to  be  on  the  retina.  The  nerve  head  is 
oblong  to  represent  astigmatism,  but  it  does  not 
have  any  relation  to  lues. 


DISEASES    OF    THE    RETINA  33 


Fig.    9.     Luetic    Retinitis.      Cross    section    Plate    VI. 

Figure  9  represents  a  cross  section  of  Plate  VI 
and  is  inserted  to  impress  upon  the  student's  mind 
the  location  of  the  pigmented  spots.  The  student 
will  recognize  that  it  is  not  a  difficult  matter  to 
determine  their  location  with  the  ophthalmoscope, 
it  being  noted  whether  the  spots  or  the  vessels 
disappear  last  when  plus  lenses  are  introduced 
into  the  ophthalmoscope.  If  the  spots  are  seen 
after  the  vessels  have  disappeared  while  increas- 
ing the  plus,  they  must  be  in  the  retina;  and,  if 
the  spots  disappear  first  they  must  be  in  the 
choroid. 

Prognosis:  If  active  but  without  too  much 
destruction  in  the  back  of  the  eye,  the  ]:)rocess  can 
often  be  arrested.  If  the  lesion  is  old,  the  same 
treatment  should  be  tried,  but  Avith  less  hope  of 
improvement. 

Treatment:  If  in  a  state  of  active  inflamma- 
tion, salvarsan  or  mercury  and  large  doses  of 
potassium  iodide  should  be  given :  but  if  inactive, 
treatment  of  any  kind  is  usually  unsatisfactory. 
Errors  of  refraction  if  any,  should,  of  course,  be 
corrected. 


34       OPHTHALMOSCOPY,    RETINOSCOPY    AND    REFRACTION 


Embolism   Central  Retinal  Artery 

Plate  VII. 


diseases  of  the  retina  35 

Embolism  of  the  Central  Artery  of  the 
Retixa:  Plate  VII.  The  nerve  liead  is  blurred 
and  there  is  a  light  area  on  its  temporal  side,  cov- 
ering the  entire  macular  region,  save  for  one  small 
red  spot.  The  patient  gives  a  history  of  sudden 
loss  of  vision. 

Figure  10  represents  a  cross  section  of  Plate 
VII.     The  student   will  note  that   there   is   no 


Fig.  10.     Embolism  Central  Retinal  Artery.     Cross  section  Plate  VII. 


elevation  of  the  fundus  shown  in  the  light  area, 
as  there  would  be  if  a  tumor,  exudate,  or  detach- 
ment of  the  retina  were  present.  (See  Plate  IV 
and  Figure  7.) 

Prognosis:  Blindness  in  the  affected  eye  with- 
out any  external  manifestations. 

Treatment:  Massage,  paracentesis  and  iodide 
of  potassium  have  been  recommended:  but  the 
results  are  usuallv  unsatisfactorv. 


36       OPHTHALMOSCOPY,    RETINOSCOPY    AND    REFRACTION 


Retinitis  Albuminurica 

Plate  VIII. 


DISEASES    OF    THE    RETINA  37 

Retinitis  Albuminurica:    Plate  VIII.  The 

nerve  head  is  not  swollen  as  in  choked  (hsc,  Plate 
XX,  XXI  and  XXII,  nor  is  it  pushed  back  as 
in  glaucoma  Plate  XXIII  and  XXIV,  hut  is 
pale  as  in  atrophy  Plate  XVIII.  The  choridal 
vessels  Avhich  are  wider  than  those  of  the  retina, 
can  be  seen  through  the  latter  and  tliere  are 
hemorrhagic  spots  scattered  throughout  the 
fimdus. 

The  principal  lesion,  which  is  described  as  a 
stellate  picture  commencing  in  tlie  macular  re- 
gion, is  typical  of  this  disease,  is  well  marked 
and  a  diagnosis  can  easily  be  made  by  anyone 
who  can  reflect  the  light  into  the  eye  and  illu- 
minate its  interior. 

While  this  picture  is  particidarly  typical,  most 
of  the  pictures  of  albuminuric  retinitis  are  not 
so  much  so.  The  student  should  examine  the  urine 
of  any  patient  in  whom  the  diagnosis  is  not  plain. 
iMany  diagnoses  are  thus  made  perfectly  clear 
where  only  a  slight  lesion  is  found  in  the  macular 
region. 

Prognosis  :    Very  grave. 

Treatment:  General  treatment  of  nephritis 
but  with  no  hope  of  restoring  vision.  The  urine, 
tonsils,  teeth,  sinuses  and  a  general  examination 
should  be  made  for  the  source  of  infection. 


39 


CHAPTER  III 

Diseases  of  the  Choroid:  The  eight  follow- 
ing pictures  fairly  represent  the  disease  of  the 
choroid.  They  should  be  carefully  observed  in 
the  model  and  the  refraction  measured  in  order 
to  be  able  to  make  the  all  important  differentia- 
tion between  excavations  and  elevations. 

If  these  eight  ]Mctures  are  carefully  studied  as 
described,  very  little  trouble  will  be  found  in 
diagnosing  diseases  of  the  choroid  when  an  exam- 
ination of  the  patient  is  made:  the  author  believes 
that  more  illustrations  would  only  complicate  the 
subject  as  designed  for  students  and  general 
practitioners  of  medicine. 


40       OPHTHALMOSCOPY,    RETINOSCOPY   AND    REFRACTION 


Coloboma   of    the    Choroid 

Plate  IX. 


DISEASES    OF    THE    CHOROID  41 

CoLOBOMA  OF  THE  Choroid:  Plate  IX.  The 
scleral  and  choroidal  rings  are  well  marked.  The 
whole  fundus  is  a  normal  red  save  in  the  lower 
part  which  is  white.  The  strongest  plus  glass 
with  wliich  the  screen  can  he  seen  on  the  red  part 
of  the  fundus  would  indicate  the  refraction  at 
that  part  of  it,  and  the  same  measurement  of  its 
white  portion  would  indicate  the  refraction  at 
that  point.  If  the  red  or  normal  part  of  the 
fundus  measured  the  same  as  the  white  it  could 
only  be  a  coloboma  of  the  choroid. 

In  this  picture,  the  choroid  is  congenitally  ab- 
sent and  the  sclera  is  seen  shining  through  the 
transparent  retina  and  the  retinal  vessels  are  seen 
with  a  white  sclera  as  a  background.  A  coloboma 
of  the  iris  is  often  found  with  a  coloboma  of  the 
choroid,  and  presents  the  picture  of  a  more  or 
less  complete  iridectomy. 

The  student  is  reminded  to  measure  the  refrac- 
tion on  the  red  part  of  the  fundus  which  is  desig- 
nated as  normal  and  without  removing  his  eye 
from  the  picture,  to  measure  that  of  the  white 
])art  of  the  fundus. 

Figure  11  represents  a  cross 
section  of  Plate  IX.  The  stu- 
dent will  contrast  tliis  ])icture 
with  figure  7  and  Plates  IV 
and  X.  Here  there  is  no  ele- 
vation above  the  normal,  while 
Fig.  11.  Coloboma  of     1^  flgurcs  ,5,  7  aud  12  the  ele- 

''s'ec«on"pYate   f£"       N^tioU   is   Wcll   Uiarkcd. 


42       OPHTHALMOSCOPY,    RETINOSCOPY   AND    REFRACTION 

Sakcoma  of  the  Choroid:  Plate  X.  The 
scleral  and  choroidal  rings  are  well  marked,  ex- 
tending all  around  the  nerve  head,  the  upper  part 
of  the  fundus  is  red  and  the  lower  part  light.  The 
retinal  arteries  are  seen  to  course  over  the  red 
part  of  the  fundus  where  the  choroid  is  giving 
the  fundus  its  red  color  as  well  as  over  the  light 
part  below,  where  there  is  something  between 
the  retina  and  the  choroid. 


Sarcoma   of   Choroid 

Plate  X. 


Hypermetropia:  The  sarcoma  is  always 
more  hypermetropic  than  the  red  or  normal  part 
of  the  fundus.  Compare  with  coloboma  of  the 
choroid  (Plate  IX),  where  there  is  a  large  hght 
area  in  the  fundus  but  which  is  not  more  hyper- 
metropic than  the  normal. 


DISEASES    OF    THE    CHOROID  43 

Vessels  in  Sakco:ma:  There  is  a  distinct  l)reak 
in  the  retinal  vessels  at  the  junction  of  the  red 
and  light  areas  such  as  is  found  in  detachment  of 
the  retina  (Plate  IV).  After  the  vessels  have 
passed  on  to  the  sarcoma,  there  are  no  hreaks  as 
are  found  in  the  former. 

Tension  in  Sarcoma:  A  sarcoma  is  not 
caused  by  low  tension  or  soft  eye  as  in  detachment 
of  the  retina  as  it  simply  grows  into  a  readily 
displaced  watery  body.  The  tension  of  the 
afiPected  eye  may  either  be  normal  or  plus  in  the 
first  stages  of  the  disease.  A  sarcoma  may  be- 
come quite  large  without  producing  increase  of 
tension,  but  later  it  always  causes  plus  tension. 

It  is  impossible  to  make  a  diagnosis  of  sarcoma 
of  the  choroid,  without  the  ophthalmoscope,  be- 
cause the  eye  does  not  show  any  symptoms 
externally.  If  the  vitreous  and  lens  are  clear  the 
diagnosis  is  plain,  especially  with  the  use  of  the 
technique  descril^ed  for  differential  diagnosis 
under  Detachment  of  the  Retina   (Plate  IV). 

Figure  12  is  a  cross  section  of  Plate  X  showing 
the  elevation  of  the  sarcoma  above  the  normal 
fundus.    A,  the  elevation;  B,  the  normal. 


Fig.   12.     Sarcoma  of  the  Choroid.     Cross  section   Plate  X. 


44      OPHTHALMOSCOPY,    RETINOSCOPY   AND   REFRACTION 


Posterior  Staphyloma  with  Choroiditis 

Plate  XI. 


DISEASES    OF    THE    CHOROID  45 


Pkognosis  :  The  growth  may  recur  in  the  eye 
socket  after  enucleation,  or  in  some  other  organ. 

Tbeatment  :  The  eye  should  be  removed  and 
with  it  as  much  of  the  optic  nerve  as  possible, 
followed  by  X-Kay  treatment.  If  the  tissues 
around  the  eye  are  involved,  all  the  structures  of 
the  orbit  should  be  removed. 

Posterior  Staphyloma  avith  Choroiditis: 
Plate  XI.  The  retinal  vessels  are  normal,  the 
scleral  ring  is  very  large,  and  the  choroidal  ring 
is  well  marked.  There  is  a  large  light  atrophic 
spot  at  the  temporal  side  of  the  nerve  head,  (pos- 
terior staphyloma)  ;  many  white  spots  are  scat- 
tered over  the  fundus,  and  the  retinal  vessels  seem 
to  run  over  them. 

The  spots  are  all  choroidal ;  and,  if  the  patient 
is  myopic,  the  retinal  vessels  could  be  seen  only 
with  a  minus  glass.  The  student  is  reminded 
that  in  Plates  V  and  VI  the  pigmented  spots 
were  in  front  of  the  retinal  vessels  wliile  in  this 
picture  the  vessels  are  in  front  of  the  spots.  In 
those  plates  the  lesions  were  in  the  retina;  but  in 
this  pictiu'e  the  lesion  is  in  the  clioroid. 

Prognosis  :    Rarely  good. 

Treatment:  Glasses  should  be  ])rescribed  if 
necessary,  but  local  treatment  of  the  eye  is  use- 
less. The  urine  should  be  examined  and  any 
general  treatment  tliat  is  indicated  should  always 
be  given,  having  in  mind  the  effects  of  lues  upon 
the  eye. 


46       OPHTHALMOSCOPY,    RETINOSCOPY    AND    REFRACTION 


Disseminated    Choroiditi 

Plate  XII. 


DISEASES    OF    THE    CHOROID  47 


DissEMiXATEJ)  CiioKOiDiTis:  Plate  Xll.  The 
scleral  and  choroidal  rings  are  well  marked  and 
the  nerve  head  is  not  swollen  as  in  choked  disc, 
(Plates  XX  and  XXI),  nor  cupped  as  in  glau- 
coma, (Plates  XXIII  and  XXIV).  The  retinal 
vessels  are  normal.  The  only  pathological  lesions 
present  are  the  atrophic  spots  in  the  choroid. 

The  sclera  can  be  seen  shining  through  the 
red  choroid  and  the  retinal  vessels  run  over  the 
atrophic  spots. 

Vision  :  The  reduction  of  vision  depends  upon 
the  location  of  the  lesion  in  the  choroid  and  the 
refraction  of  the  eye.  As  long  as  the  macular 
region  remains  free  from  disease  central  vision 
may  be  expected  to  be  retained. 

Prognosis:     Grave  if  macula  is  involved. 

Treatment  :  Constitutional  treatment  and 
correction  of  errors  of  refraction. 


48       OPHTHALMOSCOPY,    RETINOSCOPY   AND    REFRACTION 


Rupture    of    Choroid 

Plate  XIII. 


DISEASES    OF    THE    CHOROID  49 


Rupture  of  Choroid:  Plate  XIII.  The 
retinal  vessels  and  the  nerve  head  are  normal. 
There  is  an  atrophie  spot  with  a  pigmented 
horder  at  the  temporal  side  of  the  fundus. 

A  diagnosis  of  rupture  of  the  choroid,  impossi- 
ble at  the  time  of  injury  because  of  hemorrhage 
into  the  vitreous,  is  made  later  from  the  ophthal- 
moscopic picture  together  with  the  history  of 
injury. 

Vision  :  Loss  of  vision  depends  upon  the  ex- 
tent of  the  injury,  and  the  location  of  the  rupture. 
If  it  be  on  the  temporal  side,  the  loss  of  central 
vision  will  naturally  be  greater  than  w-ould  occur 
if  the  rupture  w^ere  in  some  other  part  of  the 
fundus. 

Prognosis  :  Depends  upon  the  location  of  the 
rupture ;  the  nearer  the  macula  the  less  favorable 
the  prognosis. 

Treatment:  At  the  time  of  injury  two  drops 
of  1%  solution  of  atropin  sulphate  should  he 
dro])ped  into  the  eye  three  times  a  day  together 
with  such  other  treatment  as  is  indicated.  Potas- 
sium iodide  is  indicated  for  absorption. 


50       OPHTHALMOSCOPY,    RETINOSCOPY   AND    REFRACTION 


Central  Choroiditis 

Plate   XIV. 


DISEASES    OF    THE    CHOROID  51 


Central  Choroiditis:  Plate  XIV.  The 
lesion  represented  here  is  an  extensive  choroiditis. 
It  occupies  the  entire  macular  region,  and  it 
would  be  impossible  for  anj^one  to  make  a  mis- 
take in  diagnosis,  providing  he  had  a  working 
knowledge  of  the  ophthalmoscope. 

Such  a  lesion  could  be  the  result  of  trauma  or 
any  disease  that  would  produce  a  choroiditis. 

Prognosis  :    Bad  as  regards  vision. 

Treatment  :     None. 


52       OPHTHALMOSCOPY,    RETINOSCOPY   AND    REFRACTION 


Central  Choroiditis   (slight) 

Plate  XV. 


DISEASES    OF    THE    CHOROID  53 


Central  Chokoiditis:  Plate  XV.  The 
scleral  and  choroidal  rings  are  well  marked  and 
the  retinal  vessels  and  nerve  head  are  normal. 
Three  small  wliite  spots  /ire  seen  on  the  temporal 
side  of  the  fundus  in  the  macular  region.  A 
diagnosis  of  central  choroiditis  can  he  made 
hecause  spots  in  this  region,  either  ])igmented  or 
atrophic,  are  always  the  result  of  central  choroid- 
itis. 

The  fovea  centralis  is  often  very  w^ell  marked 
hut  it  is  single  and  could  not  be  mistaken  for 
central  choroiditis. 

Vision  :  If  the  vision  is  normal  there  coidd  not 
be  a  central  choroiditis;  but  if  the  vision  is  re- 
duced, a  slight  change  in  the  macular  region  may 
be  the  cause  of  it. 

Prognosis:  The  loss  of  vision  is  usually  per- 
manent unless  a  specific  cause  is  found  and 
treated. 

Treatment:   Entirely  constitutional. 


54       OPHTHALMOSCOPY,    RETINOSCOPY   AND    REFRACTION 


Injury 

Plate  XVI. 


DISEASES    OF    THE    CHOROID  55 


Injuky — Plate  XVI.  This  picture  is  that  of 
a  perfectly  normal  fundus,  save  that  a  piece  of 
steel  has  penetrated  the  eye,  becoming  embedded 
^-  in  the  sclera  and  is  surrounded  by  blood. 

A  lesion  in  this  location  is  not  ordinarily  as 
grave  as  if  it  were  nearer  the  macula  and  pro- 
duced by  disease  (Plates  XIV  and  XV)  ;  but  in 
this  case,  the  prognosis  is  ver^^  grave  because  of 
the  lesion  liaving  been  produced  by  a  foreign 
body,  which  has  been  retained  within  the  eye  ball. 

Prognosis  :   Grave. 

Treat:ment:  Remove  the  steel  with  the  giant 
magnet  if  the  injury  is  recent  and  treat  as  any 
injury  of  the  eyeball;  sulphate  of  atropin  1%, 
2  drops  in  the  eye  three  times  a  day.  If  injury 
is  of  Ions:  standing  enucleate  the  eve.  X-Rav 
examination  shoidd  be  first  made  in  all  cases  and 
foreign  body  localized. 

It  is  not  the  purpose  of  the  author  to  describe 
the  treatment  of  injuries  of  the  eyes;  but  it  is 
always  good  practice  to  remove  eyes  that  are 
blind  and  irritated,  because  the  danger  to  the 
fellow  eye  is  all  important. 


57 


CHAPTER  IV 

Diseases  of  the  Optic  Nera:e:  The  follow- 
ing six  colored  plates  with  a  consideration  of  the 
field  of  vision  will  give  the  student  or  ])ractitioner 
a  good  practical  working  knowledge  of  diseases 
of  the  optic  nerve.  Diseases  of  the  optic  nerve 
can  often  he  diagnosed  only  hy  study  of  the  field 
of  vision  in  conjunction  with  ophthalmoscopy. 

iNIore  pictures  than  are  here  described  would 
have  a  tendency  to  confuse  the  student  and  com- 
plicate the  subject. 

A  discussion  of  the  method  of  taking  a  field 
will  be  given  on  page  76. 


58       OPHTHALMOSCOPY,    RETINOSCOPY   AND    REFRACTION 


Glaucoma  with  Atrophy 

Plate  XVII. 


DISEASES    OF    THE    OPTIC    NERVE  59 


Atrophy  of  the  Optic  Xer^^  with  Glau- 
coma: Plate  XVII.  The  scleral  and  choroidal 
rings  are  Avell  marked  but  there  is  a  marked 
difference  in  the  size  of  the  retinal  vessels.  AVliile 
the  veins  are  normal,  the  arteries  are  noted  to 
be  small  and  threadlike.  This  condition  alone 
would  justify  a  diagnosis  of  optic  atropliy:  ])ut, 
in  order  to  l)e  absolutely  certain,  tlie  field  sliould 
be  taken  in  each  eye  if  enough  vision  remains  to 
make  it  possible. 

This  plate  also  presents  a  ])icture  of  glaucoma, 
which  condition  will  be  taken  up  in  a  separate 
chapter,  the  cupping  of  the  nerve  head  being 
shown  by  the  apparent  dipping  down  of  the 
retinal  vessels  at  its  margins  and  proved  posi- 
tively by  measurement  of  the  refraction  as  de- 
scribed under  detaclmient  of  the  retina.  (Plate 
IV.) 

Prognosis:  Of  optic  atrophy  grave.  Glau- 
coma, see  page  71. 

Treatment:  Atro])hy-Salvarsan  or  mercury 
and  large  doses  of  ])otassium  iodide  may  be  tried : 
but,  if  a  positive  diagnosis  of  atro])liy  lias  been 
made,  treatment  is  usually  useless.  Stryclinia  is 
recommended  by  some. 

If  glaucoma,  see  ])age  71. 


60       OPHTHALMOSCOPY,    RETINOSCOPY   AND    REFRACTION 


Optic    Atrophy 

Plate  XVIII. 


DISEASES    OF    THE    OPTIC    NERVE  61 


Optic  Atrophy:  Plate  XVIII.  The  student 
has  been  cautioned  regarding  the  color  of  the 
optic  nerve  in  atrophy;  but,  in  this  ])icture  the 
patient  is  blind  which  ])revents  taking  the  field 
and  the  diagnosis  must  be  made  from  the  white 
disc  and  threadlike  arteries.  The  veins  are  nor- 
mal in  size. 

Field:  If  the  patient  can  see  well  enough  to 
permit  the  taking  of  the  field,  it  should  always 
be  done  in  each  eye.  When  a  concentrically 
contracted  field  is  found  the  student  can  be  sure 
of  his  diagnosis  no  matter  what  the  ophthalmo- 
scopic findings  may  be.  This  rule  should  be 
remembered. 

Arteries:  If  the  arteries  are  threadlike  and 
the  veins  normal  as  in  Plate  XVII,  a  diagnosis 
of  atrophy  can  be  positively  made  without  taking 
the  field ;  ])ut  it  is  wise  to  do  so  in  all  suspicious 
cases. 

Prognosis:  "N^ery  grave:  vision  usually  totally 
destroyed  in  time. 

Treatment:  Salvarsan  or  mercury  and  large 
doses  of  potassium  iodide  may  be  tried.  Strych- 
nia is  recommended.  ])ut  treatment  is  usually  of 
little  avail. 


62       OPHTHALMOSCOPY,    RETINOSCOPY    AND    REFRACTION 


Opaque  Nerve  Fibres 

Plate  XIX. 


DISEASES    OF    THE    OPTIC    NERVE  63 


Opaque  Ner^t:  Fibres:  Plate  XIX.  This 
picture  is  shown  in  order  to  describe  opaque 
nerve  fibres  which,  while  they  are  of  no  sig- 
nificance, should  be  recognized  when  seen,  so  that 
they  should  not  be  mistaken  for  some  patholog- 
ical condition. 

The  white  opaque  nerve  fibres  usually  follow 
the  principal  retinal  arteries.  This  is  a  normal 
condition  of  the  fundus  of  rabbits  and  is  not 
infrequently  met  with  in  man. 

In  the  human  eye  however,  so  typical  a  picture 
as  is  here  shown  is  not  frequently  observed;  more 
often  the  condition  is  present  only  in  one  or  two 
areas  adjacent  to  the  nerve  head  where  the  ves- 
sels are  covered  by  the  opaque  nerve  fibres. 


64       OPHTHALMOSCOPY,    RETINOSCOPY   AND    REFRACTION 


Plain    Choked    Disc 

Plate  XX. 


Choked  Disc  :  Plate  XX.  The  nerve  head  is 
swollen  and  the  diagnosis  can  be  made  positively 
because  when  the  fundus  is  examined,  the  re- 
fraction is  found  to  be  higher  at  the  nerve  head 
than  aAvav  from  it. 


DISEASES    OF    THE    OPTIC    NERVE 


65 


Hypermetropic  Xerve:  The  student  is  cau- 
tioned to  measure  the  refraction  of  the  fundus 
in  all  cases  at  about  one  diameter  of  the  nerve 
head  from  the  nerve  and  when  this  is  done,  to 
measure  it  at  the  edoe  of  the  nerve  head.  If  the 
latter  be  more  hypermetropic  than  the  other  parts 
of  the  fundus,  a  diagnosis  of  choked  disc  may  be 
positively  made. 

It  is  important  that  the  practitioner  make  a 
diagnosis  of  choked  disc  early  because  it  is  then 
usually  amenable  to  treatment ;  and  if  not  prop- 
erly treated,  optic  atrophy  and  blindness  may 
follow.  If  the  choked  disc  is  only  in  one  eye 
the  cause  may  be  found  in  the  sinuses;  but  if  in 
both  eyes  the  cause  must  be  looked  for  in  the 
cranial  cavity. 

Figure  13  represents  a  cross 
section  of  Plate  XX.  The 
swelling  of  the  nerve  head  can 
be  readily  seen. 

Prognosis:  Favorable,  un- 
less from  malignant  tumor  of 
the  brain. 

Treatment:  If  the  condi- 
tion is  unilateral,  which  rarely  occurs,  very  often 
appro])riate  sinus  treatment  will  effect  a  cure.  If 
l/ilateral  and  due  to  tumor  of  the  hypopliysis,  the 
gland  should  be  removed.  Usually  however,  the 
t^-eatment  offering  the  greatest  hope  of  benefit  is 
the  administration  of  salvarsan  or  mercury  with 
large  doses  of  potassium  iodide. 


Fig.  13.    Choked  Disc. 

Cross      section      Plate 

XX. 


66       OPHTHALMOSCOPY,    RETINOSCOPY   AND    REFRACTION 


Neurorentinitis 

Plate  XXI. 


DISEASES    OF    THE    OPTIC    NERVE  67 


Neuroretixitis:  Plate  XXI.  The  only 
difference  between  this  picture  and  Plate  XX,  is 
the  twisting  of  the  retinal  vessels  and  more  swell- 
ing of  the  optic  nerve.  The  nerve  head  is  swollen 
and  the  retinal  vessels  are  tortuous.  The  diag- 
nosis is  that  of  a  lesion  both  of  the  optic  nerve 
and  the  retina  (Xeurorettxitls)  . 


Fig.  14.     Choked  disc.     Cross  section  Plate  XXI. 

Figure  14  represents  a  cross  section  of  Plate 
XXI.  The  diagnosis  is  readily  made  from  the 
swelling  of  the  nerve  and  the  twisting  of  tlie  ret- 
inal vessels. 

Prognosis:    Is  the  same  as  in  Plate  XX. 

Treatment:    Is  the  same  as  in  Plate  XX. 


68       OPHTHALMOSCOPY,    RETINOSCOPY   AND    REFRACTION 


Papillitis    Haemorrhagica 

Plate  XXII. 


DISEASES    OF    THE    OPTIC    NERVE  69 


Papillitis  Hemorrhagica:  Plate  XXII. 
The  nerve  head  is  swollen,  the  retinal  vessels  are 
twisted  as  in  Plate  XXI  and  tlie  fundus  is  stud- 
ded with  hemorrhages  some  of  whieh  are  lighter 
than  others,  indieating  their  more  recent  occur- 
rence. 


Fig.    15.     Papillitis    Hemorrhagica.      Cross    section    Plate    XXII. 

Figure  1.5  represents  a  cross  section  of  Plate 
XXII.  If  the  media  are  clear,  a  diagnosis  can 
readih^  be  made  and  the  amount  of  swelling  of 
the  nerve  can  be  readily  measured  Avith  the 
ophthalmoscope. 

Prognosis:     Is  the  same  as  in  Plate  XX. 

Treatment:    Is  the  same  as  in  Plate  XX. 


70       OPHTHALMOSCOPY,    RETINOSCOPY   AND    REFRACTION 


Glaucoma 

Plate  XXIII. 


DISEASES    OF    THE    OPTIC    NERVE  71 

Glaucoma:  Plate  XXIll.  The  retinal  ves- 
sels are  normal  in  size  but  they  do  not  emerge 
from  the  center  of  the  nerve  as  in  normal  eyes, 
(Plates  1  and  11)  but  seem  to  stop  and  disappear 
at  the  edge  of  the  nerve  head. 

If  the  eye  is  refracted,  the  bottom  of  the  cup 
or  center  of  the  nerve  head  will  be  found  to  be 
more  myopic  than  the  surrounding  fundus.  The 
arteries  may  pulsate  and  the  field  is  usually  con- 
tracted and  to  the  nasal  side. 

In  such  a  case  the  tension  may  be  high,  the 
cornea  anesthetic,  the  anterior  chamber  hazy  and 
shallow,  the  lens  clear,  the  vitreous  clear,  but  the 
ophthalmoscope  discloses  this  typical .  picture  of 
glaucoma. 


Fig.   16.     Glaucoma.     Cross  section  Plate  XXIII. 

Figure  16  is  a  cross  section  of  Plate  XXIII; 
there  is  a  pushing  back  of  the  nerve  head.  The 
excavation  can  be  as  readily  measured  as  an  ele- 
vation was  measured  in  the  other  plates.  The 
difference  in  refraction  between  the  normal  part 
of  the  fundus  and  tlie  bottom  of  the  depression 
will  represent  the  depth  of  the  cupping. 

Prognosis:  Guarded — seepage  112. 

Treatment:  See  page  112. 


72       OPHTHALxMOSCOPY,    RETINOSCOPY    AND    REFRACTION 


Haemorrhagic  Glaucoma 

Plate  XXIV. 


DISEASES    OF    THE    OPTIC    NERVE  73 


Hemorrhagic  Glaucoma:  Plate  XXIV. 
Tlie  retinal  vessels  are  normal  in  size  but  do  not 
emerge  from  the  center  of  the  optic  nerve  as  in 
normal  eyes.  (Plates  I  and  II.)  They  appear 
to  stop  at,  and  dip  back  from  the  edge  of  the 
optic  nerve.  (Plate  XXIII.)  The  center  of 
the  optic  nerve  is  more  myopic  than  the  normal 
part  of  the  fundus  and  hemorrhages  can  be  seen, 
some  dark  and  some  liglit,  the  latter  being  more 
recent. 


Fig.    17.     Hemorrhagic    Glaucoma.      Cross    section    Plate    XXIV. 

Figure  17  represents  a  cross  section  of  Plate 
XXIV;  the  cupping  can  be  readilv  measured  as 
in  Plate  XXIII. 

Prognosis:  Grave.    See  page  112. 

Treatment:  See  page  112. 


FIELD  OF  VISION 
Direct  and  Indirect  Ophthalmoscopy 

CHAPTER  V. 

The  Field  of  Vision:  The  field  must  be 
studied  in  connection  with  ophthahiioscopy,  be- 
cause some  diseases  of  the  fundus  that  at  first 
seem  obscure,  are  made  perfectly  clear  when  the 
field  is  considered;  and  there  are  some  diseases 
that  are  impossible  to  diagnose  without  the  tak- 
ing of  the  field. 

Without  A  Perimeter:  The  first  thing  to 
do  in  taking  the  field  without  a  perimeter  will 
be  to  take  a  small  piece  of  paper,  one  quarter 
of  an  inch  square,  red  on  one  side  and  white  on 
the  other.  Hold  it  in  front  of  the  patient  by 
inserting  it  between  the  points  of  a  pen  (Fig 
18)  and  see  if  he  is  color  blind. 


FIELD    OF    VISION 


75 


Fig.    IS.     Testing    field   for   colors 


76      OPHTHALMOSCOPY,    RETINOSCOPY    AND    REFRACTION 

Central  Scotoma  for  Red:  The  examiner 
rotates  the  penholder  and  the  red  and  white  are 
alternated.  When  the  patient  looks  directly  at 
the  paper  he  is  instructed  to  cover  one  eye  and 
look  into  the  examiner's  eye  with  the  other.  If 
the  red  color  does  not  appear  red  when  placed 
in  his  direct  vision,  or  between  the  examiner's  eye 
and  that  of  the  patient,  and  does  seem  so  to  him 
when  the  paper  is  moved  away  from  the  center  of 
his  field,  he  has  a  central  scotoma  for  red. 

Treatment:  Remove  the  cause  which  is 
usually  alcohol  or  tobacco  and  give  eliminatives 
and  1/30  grain  sulphate  of  strychnine  qid. 

If  there  is  no  central  scotoma  for  red,  next 
determine  the  extent  of  the  fields  for  the  various 
colors  by  comparison  with  your  ow^n. 

To  test  the  right  eye,  the  patient  is  placed  in 
such  a  position  that  his  eyes  will  be  on  a  level 
with  the  examiner's  eyes;  and  the  light  from  the 
window  will  fall  equally  on  his  right  and  on  the 
examiner's  left  side.  The  examiner's  right  and 
the  patient's  left  eye  should  be  closed  and  both 
should  look  steadily  at  the  pupil  of  the  other. 
(Figure  19) .  The  positions  are  reversed  for  ex- 
amination of  the  left  eye,  in  order  that  proper 
illumination  may  be  obtained. 

Figure  19.  Comparison  of  Examiner's  and 
Patient's  fields.  A  piece  of  paper,  red  on  both 
sides  and  one-quarter  inch  in  diameter  is  now 
inserted  into  the  pen.  This  paper  should  be 
moved  in  a  plane  midway  between  the  examiner's 
eye  and  that  of  the  patient,  the  examiner  and 
patient   looking   into   each   other's   eyes.     Both 


FIELD    OF    VISION 


77 


Fig.   19.     Taking   field   without   Perimeter 


78      OPHTHALMOSCOPY,    RETINOSCOPY   AND    REFRACTION 

should  see  the  paper  and  distinguish  its  color 
about  the  same  time  if  both  have  normal  fields. 

This  can  be  done  with  white  as  well  as  with  all 
the  colors  and,  if  the  field  is  carefully  taken,  the 
student  will  be  able  to  detect  any  deviation  from 
the  normal. 

With  Perimeter:  If  the  field  seems  sus- 
picious with  this  examination,  it  should  be  taken 
with  the  perimeter  (Figure  20  and  21)  or  with 
the  campimeter  (Figure  22). 


Fig.    20.        Perimeter     (Meyrowitz), 


Fig.    21.         Perimeter     (Geneva). 


A  number  of  abnormal  fields  that  are  typical 
of  the  conditions  in  which  they  are  found  are 
inserted  for  the  consideration  of  the  student  and 
that  he  may  properly  appreciate  them  a  normal 
field  is  shown. 


FIELD    OF    VISION 


79 


Fig.   22.      Ciimpimeter 


Fig.    23.     Normal    Field    (Jennings) 


Fig.  24.  The  field  of  vision  in 
Glaucoma.  Left  eye.  Peripheral 
contraction  especially  on  the  nasal 
side.      (May) 


80       OPHTHALMOSCOPY,    RETINOSCOPY   AND    REFRACTION 


He  will  note  especially  the  extent  of  the  in- 
dividual fields  for  the  various  primary  colors 
tested  for.  All  of  which  were  tested  with  discs 
1/4  inch  in  diameter. 

Glaucoma  :  The  field  is  contracted  below  and 
to  the  nasal  side. 

For  prognosis  and  treatment  see  page  112. 

Optic  Atrophy:  The  field  is  concentrically 
contracted  for  white  and  colors. 

Prognosis :     Grave. 


Fig.  25.  Field  of  vision  of  the  right  eye  in  a  case  of  optic-nerve  atrophy. 
The  white  field  is  slightly  contracted,  the  color  fields  markedly  restricted. 
(deSchweinitz) 

Treatment:  Mercury  and  Iodide  of  Potas- 
sium should  be  given  a  trial.  Strychnia  is  also 
recommended. 


MKIJ)    OK    VISION 


81 


'nk 


Fig.    26    and    27.     Homonymous     Hemiopia     (^Schweigger) 

Hkmixopsia:  Fio-.  2i\  and  Fig.  27.  'I'hc  fields 
are  entirely  cnt  off  on  one  side. 

Fields  in  right  homonymous  heminopsia. 

Pkoqnosis:    Fields  usually  remain  unchanged. 

Tkeatment:     If  specific,  salvarsan,  mercury 

and  large  doses  of  iodide  of  ])otassium.     If  in 

elderly  patients  and  of  unknown  causation,  give 

fifteen  grains  of  the  latter  four  times  daily. 

Retkobular  Xeuritis  : 
Toxic  Amblyopia:  There 
is  a  spot  in  the  center  of  the 
field  where  the  ])atient  can- 
not recognize  the  color  of  a 
small  piece  of  red  ])aper — 
central  scotoma  for  red. 

Figure  28.  Field  in  Uet- 
rohular  Xeuritis. 

Prognosis:       Good     if 
treated  early. 

Treatment:  Remove  the  cause  which  is  usu- 
all}^  tobacco  or  alcohol  or  l)()th  and  give  strychnia 
per  mouth  or  hypodermically. 


Fig.   28.     Field  in  Toxic  Am 
blyopia.      (F^chs) 


82       OPHTHALMOSCOPY,    RETINOSCOPY   AND    REFRACTION 

Hysteria:  The  fields  overlap,  that  is,  the 
green  which  usually  lies  wholly  within  that  for 
the  red  is  found  to  be  larger  and  overlapping 
it  in  places.  It  also  changes  at  different  exami- 
nations or  even  when  successively  taken  at  the 
same  sitting.  When  the  field  is  being  taken, 
even  if  carefully  done,  it  will  a])pear  to  change. 
The  following  two  very  different  fields  were  se- 
cured by  a  careful  operator  within  an  hour  on 
a  patient  with  a  well  authenticated  diagnosis  of 
hysteria. 

Figure  29.  Field  in  Hysteria.  Figure  30. 
Field  in  the  same  case  one  hour  later.  Such  a 
variation  would  not  occur  in  other  diseases,  and 
the  general  practitioner  should  understand  this 
important  condition. 

Prognosis  :  Good.  However,  the  patient  will 
often  complain  that  the  vision  is  much  impaired 
or  even  sometimes  claim  nearly  complete  blind- 
ness. 


Fig.    29.     Field    in    Hysteria  Fig.    30.     Field   in   Hysteria 


FIELD    OF    VISION 


83 


Treatment:  Prescribe  the  proper  glasses  for 
the  correction  of  any  refractive  error  found,  and 
give  the  general  treatment  indicated  for  this  con- 
dition. Some  placebo  may  be  dropped  into  the 
eyes  as  for  instance,  sodii  biboratis  gr.  V  to  oz. 
one  everv  three  liours. 


Fig.    31.      Oblique  Illumination 


o4       OPHTHALMOSCOPY,    RETINOSCOPY   AND    REFRACTION 

Systematic  Eye  Examination:  When  the 
student  has  mastered  the  schematic  eye,  he  will 
be  prepared  to  examine  a  patient;  but  it  is  un- 
wise to  attempt  to  do  so  until  he  finds  the 
schematic  eye  easy  to  examine,  even  with  a  small 
pupil  and  has  mastered  the  technique  of  oblique 
illumination  which  he  will  find  useful  in  all  cases 
as  well  as  ophthalmoscopy. 

Oblique  Illumination:  Condensing  lens 
used  in  indirect  ophthalmoscopy.  Illumination 
of  the  part  under  inspection  by  means  of  a  strong 
convex  lens.  By  this  means,  the  illumination  is 
markedly  increased  and  minute  details  are  made 
visible.  This  method  of  examination  is  always 
used  for  searcliing  for  foreign  bodies  upon  or  in 
the  cornea. 

Light  :  The  source  of  light  can  be  from  a  gas, 
kerosene,  candle  or  electric  liglit,  with  a  frosted 
globe  or  the  light  from  a  window.  The  con- 
densing lens  used  in  connection  with  direct 
ophthalmoscopy  can  be  used  for  condensing  the 
rays  of  light. 

Indirect  O p hth alm  oscopy 

When  practicing  indirect  ophthalmoscopy 
(Figure  32)  the  patient  is  requested  to  look  be- 
yond the  student's  right  ear  when  the  right  eye  is 
examined,  or  left  ear  if  the  left  eye  is  examined: 
the  light  is  reflected  into  the  eye  from  a  distance 
of  about  twenty  inches  with  the  mirror  of  the 
ophthalmosco])e  tilted  towards  the  light  in  the 
same  manner  as  in  the  study  of  the  schematic 
eye.     A  +  3  D.  lens  is  placed  in  the  ophthal- 


FIKLD    OF    VISION 


85 


mosc()])e  and  a  -f^  20  1).  -that  used  for  bifocal 
examination — is  held  two  inches  in  front  of  the 
patient's  eye,  when  an  inverted  picture  of  the 
fundus  will  be  seen  in  front  of  the  +  20  1). 
lens.  The  whole  fundus  can  be  studied  in  this 
manner  and  all  parts  of  it  can  be  brought  into 


Fig.    ;i2.      Indirect    Ophthalmoscopy 


86       OPHTHALMOSCOPY,    RETINOSCOPY   AND    REFRACTION 

view  by  moving  the  +  20  D.  lens  from  side  to 
side  and  up  and  down. 

The  indirect  method  is  usually  employed  when 
the  eyes  of  children  are  to  be  examined,  or  when 
the  patient  has  lost  the  vision  of  one  eye;  and 
in  all  other  e^^es  where  the  direct  method  cannot 
be  employed. 

Direct  Ophthalmoscopy.  First  Position: 
Figure  33.  Represents  the  correct  first  position 
of  observer  and  observed  in  practicing  direct 
ophthalmoscopy.  The  same  rules  are  to  be  ob- 
served as  when  the  model  is  being  used.  To 
examine  the  right  eye,  the  light  is  placed  on  the 
patient's  right  side  on  a  level  with  his  eye. 

Position  of  Observer:  When  the  right  eye 
is  to  be  examined  the  observer  sits  in  front  and  to 
the  right  on  a  revolving  stool  that  has  been  ad- 
justed to  the  proper  height.  Before  beginning 
the  ophthalmoscopic  examination,  the  patient  is 
instructed  to  look  across  the  room  at  some  fixed 
point  and  is  also  told  to  close  both  eyes  if  the 
observer  should  get  in  front  of  him,  thus  keeping 
him  from  seeing  the  object  selected.  The  student 
will  soon  learn  to  keep  his  head  out  of  the 
patient's  line  of  vision  and  will  readily  acquire  a 
good  position  for  examination. 

The  patient  will  always  keep  his  eye  quiet  and 
in  one  position  if  he  has  something  for  the  un- 
observed eye  to  look  at  and  he  should  always  be 
instructed  to  look  at  some  selected  spot  before 
beginning  the  ophthalmoscopic  examination. 
The  mirror  of  the  ophthalmoscope  is  tilted  to- 
wards the  light  which  is  now  reflected  into  the  eye 


FIELD    OF    VISION 


87 


FiK     33.     Direct    Ophthalmoscopy.    First    position 


88       OPHTHALMOSCOPY,    RETINOSCOPY    AND    REFRACTION 


Fig.   34      Direct    Ophthalmoscopy.      Second    position 


FIELD    OF    VISION  89 

under  examination.  As  soon  as  the  light  is  re- 
Heeted  into  the  eye,  the  pupil  will  appear  red 
and  the  approach  to  the  second  position  is  begun. 

Second  Posijiox  :  Figure  84.  llepi-esents 
the  second  position  lor  dn*ect  ophthalmoscopy. 
The  student  approaches  the  patient  from  the  first 
position  and  comes  as  close  to  the  o])served  eye 
as  possible  without  losing  the  red  reflex.  The 
student  must  keep  both  of  his  eyes  open  and  relax 
his  accommodation  as  mucli  as  possible  by  look- 
ing into  the  distance.  If  the  refraction  of  the 
eye  is  normal  or  hypermetropic,  the  student  will 
readily  obser^'e  the  retinal  vessels  and  optic  nerve 
when  the  first  thing  to  be  done  before  losing  sight 
of  them  is  to  refract  the  eye.  If  the  eye  be 
myopic,  the  details  of  the  fundus  can  be  seen  only 
with  minus  glasses. 

Light  Streaks  ok  White  Lines:  It  is  es- 
sential to  get  an  ophthalmoscopic  ])icture  that  is 
not  exaggerated,  and  to  do  this  the  student  must 
refract  the  eye  as  he  begins  his  ophthalmoscopic 
examination  by  looking  through  the  a])erture  of 
the  instrument.  If  the  light  streaks  on  the  retinal 
vessels  can  be  seen  with  the  ()phthalmosco])e  in 
this  manner,  the  eye  is  either  normal  or  hy])er- 
metro])ic. 

The  student   should  now   add  1    1).   to  his 

ophthalmoscope  and,  if  the  white  lines  on  the 
arteries  disappear,  he  will  know  he  is  dealing 
with  a  normal  eye:  but,  if  they  can  be  seen  with 
a  +  1  D.,  he  will  know  lie  is  dealing  with  a 
hy])ermetro])ic  eye  and  must  ])ut  on  stronger  plus 
lenses    until    the    white    lines    disappear.      The 


90       OPHTHALMOSCOPY,    RETINOSCOPY   AND    REFRACTION 

strongest  plus  glass  with  which  the  light  streaks 
or  white  lines  can  be  seen  at  all,  will  represent 
the  amount  of  hypermetropia. 

If  the  eye  is  myopic,  the  weakest  minus  glass 
with  which  the  white  lines  on  the  retinal  vessels 
can  be  seen  at  all  will  represent  the  amount  of 
myopia. 

^^^ith  these  two  rules  in  mind  at  all  times,  the 
student  can  readily  detect  elevations  and  exca- 
vations in  the  fundus,  and,  when  this  is  done,  he 
will  be  quite  well  prepared  to  make  diagnosis 
of  gross  pathological  lesions. 

He  will  be  able  to  diagnose  a  swelling  of  the 
nerve  head,  a  cupping  of  it,  or  an  elevation  of 
any  part  of  the  fundus.  He  will  also  be  able 
to  tell  whether  spots,  either  white  or  black,  are 
situated  in  the  retina,  in  front  of  the  retinal  ves- 
sels, or  in  the  choroid — back  of  them. 

The  student  must  observe  the  eye  at  close 
range  which  means  that  he  should  get  as  close 
to  it  as  possible. 

Description  of  the  Human  Fundus  :  The 
picture  of  the  himian  fundus  cannot  be  described 
because  of  the  great  variations  in  its  color.  The 
student  will  observe  the  same  general  normal 
points  as  he  did  in  the  pictures  in  the  schematic 
eye.  He  will  observe  the  optic  nerve  with  the 
retinal  vessels  emerging  from  the  center  of  it  and 
passing  across  the  fundus.  If  the  retinal  vessels 
all  stop  abruptly  at  the  edge  of  the  disc,  it  is  a 
picture  of  glaucoma  w^hich  the  student  learned 
to  recognize  in  the  schematic  eve.  (Plate 
XXIII.) 


FIELD    OF    VISION  91 

If  the  retinal  vessels  are  tortuous,  a  picture  of 
retinitis  will  be  recognized  as  was  learned  in  the 
study  of  the  model.  (Plate  XXI-XXII.)  If 
the  nerve  head  is  more  hypermetropic  than  the 
normal  part  of  the  fundus  the  student  knows 
he  is  dealing"  with  a  case  of  choked  disc.  (I'ig- 
13.)  All  this  he  has  learned  in  the  examination 
of  the  schematic  eye. 

If  some  ])arts  of  the  fundus  are  much  lighter 
in  color  than  othei-s,  and  it  is  higher  at  the  light 
places  than  at  other  portions,  the  observer  will 
at  once  be  suspicious  of  either  detachment  of 
the  retina,  an  exudate,  or  sarcoma  of  the  choroid. 
The  student  is  referred  to  the  descri])tion  of  these 
two  pictures.  (Plates  IV  and  X)  which  are  the 
same  as  the  pictures  of  the  same  lesion  in  the 
human  fundus. 

If  the  student  has  mastered  the  schematic  eye, 
he  will  experience  no  more  trouble  in  making 
diagnosis  of  diseases  of  the  interior  of  the  eve 
than  he  will  in  making  diagnosis  of  external 
diseases.  ]Many  doctors  take  the  schematic  eye 
too  lightly  and  want  to  practice  on  patients 
before  they  have  mastered  it.  Too  great  stress 
cannot  be  placed  u])on  tlie  thorough  study  of  the 
schematic  eye. 

Ophthalmoscopy  will  be  simplified  if  tlie  hu- 
man eye  is  not  studied  until  the  student  can 
examine  the  schematic  eye  without  any  effort. 
If  he  will  then  begin  work  on  ])atients,  he  will 
find  little  difficulty  in  getting  a  good  view  of 
the  fundus. 


92       OPHTHALMOSCOPY,    RETINOSCOPY    AND    REFRACTION 

The  cases  that  appear  obscure  to  a  beginner  in 
ophthahnoscop}^  usually  are  so  because  of  his 
inability  to  illuminate  the  interior  of  the  eye  and 
see  the  pictures.  If  they  can  be  seen,  diagnosis 
will  be  made  simple  and  interesting.  If  diagnosis 
of  diseases  of  the  interior  of  the  eye  is  to  be  made 
simple,  there  is  only  one  way  to  do  it  and  that  is 
to  make  ophthalmoscopy  easy,  which  can  only  be 
done  by  becoming  master  of  the  o])hthalmoscope 
upon  the  model. 

Retinal  Artekies  Instead  of  Screen  :  The 
student  will  have  the  retinal  vessel  to  deal  with  in 
the  human  eye,  and  he  will  have  lost  the  screen, 
v/liicli  he  has  been  examining  in  the  schematic 
eye.  He  will  now  substitute  the  white  streaks 
on  the  retinal  arteries  for  the  screen  and  examine 
the  human  eye  in  the  same  manner  as  he  did 
when  dealing  with  the  model. 

The  Same  Two  Ruees  to  Remember:  First, 
the  strongi'st  plus  Jens  xcith  zdiieJi  he  ean  see 
the  tchite  streaks  on  the  retinal  arteries  AT  ALL 
icill  measure  the  hypermetropia.  Second,  the 
rceakest  fuinus  glass  tcith  ichieh  lie  ean  see  the 
xchite  streaks  on  the  retinal  arteries  AT  ALL 
tcill  measure  the  myopia.  THESE  TWO 
RULES  MUST  BE  REMEMBERED. 

Distance  of  Examiner  From  Patient; 
The  examiner  should  get  as  close  as  possible  to 
the  eye  to  be  examined  and  at  the  same  time  not 
to  lose  his  light.  The  patient's  eyes  should  be 
examined  in  the  same  manner  and  the  same  two 
rules  observed  as  in  the  examination  of  tlie 
schematic  eye. 


FIELD    OF    VISION  93 

Where  Should  the  Patient  J.ook:  It  is 
of  the  greatest  iin})ortance  that  the  ])atient  I)e 
told  to  look  at  some  point  on  the  opposite  side  of 
the  room.  If  the  patient  looks  at  this  point  and 
the  observer  sits  at  the  side  and  not  in  front  of 
him,  he  will  hold  the  eye  perfectly  quiet. 

If  the  observer  gets  in  front  of  the  patient 
and  prevents  him  from  seeing  the  ol)ject  given 
him  to  look  at,  the  eye  that  is  being  observed 
will  move  and  the  student  will  have  difficulty  in 
examining  it;  but  as  long  as  the  patient  has  a 
fixed  point  to  observe  with  the  eye  that  it  is  not 
being  examined  there  will  be  no  difficulty. 

A  beginner  in  ophthalmosco])y  should  have  the 
])atient  look  at  some  object  on  the  o])posite  wall 
and  instruct  him  to  shut  both  of  his  eyes  and 
keep  them  shut,  if  the  observer's  head  obstructs 
his  vision  and  kee])s  liim  from  seeing  tlie  object. 
In  this  manner  the  student  will  soon  acc^uire 
an  easy  and  correct  ])osition  for  the  examination 
of  an  eye  with  the  ophthalmoscope. 

Where  Should  the  Exa:mtxer  Look:  The 
examiner  should  keep  both  eyes  o])en  and  imagine 
tlie  picture  he  is  examining  to  l)e  twenty  or  more 
feet  from  him.  He  will  in  this  manner  learn  to 
relax  his  accommodation. 

Accovi:m()DATK)X  :  This  is  a  great  bugbear  to 
a  beginner.  He  becomes  confused  and  thinks  he 
must  be  acciu'ate  in  his  measurements  in  order 
to  be  able  to  make  diagnosis  of  })at]iological 
lesions.  On  the  contrary,  tlie  ])rincipal  thing 
necessary  for  him  to  do  is  to  be  able  to  recog- 
nize elevations  and  excavations  in  the  back  part  of 


94       OPHTHALMOSCOPY,    RETINOSCOPY    AND    REFPIACTION 

the  eye.  To  do  this,  it  is  imperative  that  he  be 
able  to  measure  the  refraction  at  some  normal 
point,  and  afterward  to  measure  it  at  the  ab- 
normal part  witliout  removing  liis  eye  from  the 
ophthalmoscope  or  changing  his  position. 

If  the  student  makes  a  mistake  in  measuring 
the  normal  part  of  the  fundus,  he  very  likelj^  will 
make  the  same  error  in  measuring  the  abnormal 
part.  The  only  necessary  thing  to  know  is  the 
difference  between  the  two  points,  and  he  will 
soon  find  this  not  at  all  difficult. 

For  instance,  if  the  student  is  examining  a 
swollen  nerve,  he  first  measures  the  refraction  of 
a  normal  part  of  the  fundus,  usually  about  one 
diameter  of  the  nerve  head  from  it;  he  then 
measures  that  of  the  head  of  the  nerve  and  the 
difference  noted  will  represent  the  swelling  of 
the  nerve  head. 

If  the  normal  part  of  the  fundus  as  measured 
by  the  student  is  +  3D.  and  the  nerve  head 
+  9  D.,  he  will  have  6  D.  swelling.  If  he  has 
made  a  mistake  and  had  measured  the  normal 
part  of  the  fundus  +  6  D.,  would  have  made 
the  same  error  at  the  nerve  head  and  measured 
it  a  +  12.  D.  The  difference  would  be  the  same 
and  in  either  case  he  would  have  6  D.  or  two  milli- 
meters of  swelling  of  the  nerve  head.  Other  ele- 
vations would  be  measured  in  a  similar  manner. 

Examination  of  Xormal  Eyes:  The  stu- 
dent should  examine  as  many  normal  eyes  as 
possible  because  there  is  no  better  practice  with 
the  ophthalmoscope.     The  principal  thing  for  a 


FIELD    OF    VISION  95 

beginner  to  do,  when  making  an  ophthalmoscopic 
examination  is  to  measure  the  refraction. 

He  should  first  find  the  vessels  in  the  fundus 
and  then  look  for  the  light  streaks  on  tlie  retinal 
arteries  and  practice  adding  ])lus  lenses  in  his 
ophthalmoscope  until  they  disappear. 

If  he  cannot  see  the  light  streaks  on  the  retinal 
arteries  and  must  put  on  minus  lenses  to  bring 
them  out,  he  is  dealing  Avith  myopic  eyes.  He 
should  ])ractice  ])utting  on  minus  lenses  to  bring 
out  the  light  streak  on  the  retinal  arteries  remem- 
bering that  the  weakest  one  with  which  this  can 
be  done  is  the  measure  of  the  myopia. 

If  the  student  will  measure  the  refraction  in 
every  eye  he  examines,  he  will  soon  be  able  to 
recognize  a  normal  fundus;  and,  when  this  is 
accomplished,  there  Avill  be  very  little  trouble  in 
detecting  existing  lesions. 

Elevations  and  excavations  can  easily  be  meas- 
ured when  the  student  illuminates  the  interior 
of  the  eye  and  can  measure  the  normal  fundus. 
When  this  is  accom])lished,  a  choked  disc,  a  glau- 
coma, a  detached  retina,  an  albuminuric  retinitis, 
or  a  sarcoma  of  the  choroid  will  be  very  simple 
matters  to  diagnose. 

XoT  Xecessary  to  Remember  Pictures:  It 
will  not  be  necessary  to  remember  the  picture  of 
a  lesion  as  seen  with  the  ophthalmoscope,  but 
rather  to  know  when  a  fundus  is  normal,  and  if 
abnormal,  to  be  able  to  point  out  the  abnormal 
])oints. 

Color  of  the  Fundus:  The  general  back- 
ground of  the  fundus  is  red  but  it  may  be  very 


96       OPHTHALMOSCOPY,    RETINOSCOPY    AND    REFRACTION 

dark  or  it  may  be  very  light  red.  The  retina 
is  a  transparent  membrane  and  the  color  of  the 
fundus  is  produced  by  the  vascular  choroid. 

The  normal  nerve  head  sometimes  appears  red, 
or  hyperaemic,  and  sometimes  light,  or  anaemic. 
If  the  patient  has  normal  vision,  tlie  student 
l^hould  not  pay  much  attention  to  the  color  of 
the  optic  nerve;  but  if  the  vision  is  ])oor,  it  should 
be  studied  carefully. 

Optic  Atrophy:  In  atrophy  of  the  optic 
nerve,  the  nerve  head  is  white  or  gray;  but  the 
student  should  never  depend  upon  the  color  of 
the  nerve  head  alone. 

If  he  is  suspicious  of  optic  atrophy,  the  field 
should  be  taken  if  the  patient  has  enough  vision 
to  make  this  possible.  If  the  patient  is  not 
blind,  the  student  can  note  the  color  of  the  nerve 
head  but  he  can  make  a  diagnosis  of  atrophy 
of  the  optic  nerve  by  taking  his  field  of  vision 
long  before  he  could  be  siu'e  of  such  a  diagnosis 
with  the  ophthalmoscope.  Fields  of  both  eyes 
should  be  taken  if  the  patient  has  sufficient  vision ; 
but  if  one  eye  is  blind,  the  field  of  the  good  one 
should  be  taken. 


97 


CHAP  IKK   VI. 

Systematic  Kxamixatiox  of  tiii:  \\y\: 

It  would  be  impossible  to  make  a  systematic 
examination  of  the  eye  without  a  Avorking  knowl- 
i^dge  of  the  oj)hthalm()sc()])e:  i)iit  even  wliilc  wv 
can  make  use  of  this  small,  inexpensive  and  im- 
])ortant  instrument,  we  have  not  as  yet  descril)ed 
any  systematic  method  of  examination  witliout 
the  careful  following  of  which  many  im])ortant 
tilings  woidd  be  overlooked.  This  systematic 
examination  should  be  commenced  from  the  front 
and  proceed  backward  by  certain  definitely  fixed 
steps. 

First  Step:  Inspection:  Figure  So.  In- 
spection should  cover  all  that  can  be  seen  without 
instruments,  and  a  good  light  Fig.  Ho  A  is  indis- 
pensable. The  cornea  is  the  first  structure  exam- 
ined from  front  backwards.  It  is  the  seat  of  a 
great  many  eye  affections  coming  under  the  care 
of  general  practitioners  and  should  always  receive 
a  very  careful  examination  for  foreign  bodies, 
ulcers  and  o]:)acities. 

The  antci-ioi-  chamber  sliould  l)e  examined  for 
o])acities  and  the  ii'is  and  pu])il  sliould  be  ex- 
amined together. 

The  ])U])il  sliould  dilate  Avhen  covei'ed  or  pro- 
tected from  the  light  and  contract  to  the  light 
when  uncovered  oi*  when  a  light  is  reflected  into 
the  eye.  After  the  anterior  ])art  of  the  eve  ball 
has  been  inspected  and  the  tension  noted  (  Figs.  87 
tnid  41 ),  the  lower  lid  should  be  drawn  down;  the 


98       OPHTHALMOSCOPY,    RETINOSCOPY    AND    REFRACTION 


Fig.    35.     Systematic    Examination    of    the    Eye 


,,,ss«*^^  V,   MUELLER      i      CO      I 


jTrta 


Fig.   35a.     Light 


SYSTEMATIC    EXAMINATION    OF    THE    EYE  99 

conjunctiva  inspected  and  the  lachrymal  sac 
pressed  down.     (  Figure  36.) 

If  pus  be  pressed  out  of  the  lachrymal  sac, 
a  diagnosis  of  dacyryocystitis  Avill  be  made  ( Fig. 
36).  The  upper  lid  should  be  everted  for  exami- 
nation by  drawing  it  downward  and  away  from 
the  eye  and  turning  it  over  a  pencil.  The  motility 
of  the  e3^es  can  be  observed  by  having  the  ])atient 
look  up,  down,  right  and  left.  If  a  diagnosis 
has  not  as  yet  been  arrived  at,  the  vision  should 
be  taken  and  a  careful  manifest  refraction  made. 

jMany  doctors  are  satisfied  with  an  examination 
less  accurate  than  has  been  described,  but  those 
who  can  use  the  o])hthalmosco])e  realize  that  a 
systematic  examination  has  only  been  begun  and 
that  what  is  to  follow,  while  not  difficult,  is  of 
very  great  im])ortance. 

Second  Step:  The  patient  is  now  taken  to 
the  dark  room,  and,  with  a  -f-  20  D.  lens 
that  accompanies  the  ophthalmoscope,  the  light 
is  condensed  into  the  eye  and  the  cornea,  anterior 
chamber,  iris,  pupil  and  lens  are  again  inspected; 
and,  if  the  cause  of  the  trouble  be  not  determined, 
the  third  step  should  be  begun. 

Third  Step:  Tlie  eye  has  now  been  examined 
from  front  backwards  to  the  lens  and  we  are 
ready  for  the  most  interesting  and  satisfactory 
l)art  of  an  examination  of  the  eyes,  the  use  of 
the  ophthalmosco])e.  The  first  structure  to  be 
examined  in  the  third  step  is  the  lens.  This  is 
done  with  the  +  16  D.  of  the  smaller  disc  ro- 
tated to  position  beliind  the  aperture  of  tlie  in- 
strument. 


100    OPHTHALMOSCOPY,    RETINOSCOPY    AND    REFRACTION 


Fig.  36.     Pressing  upon  the  Lachrymal  Sac. 


SYSTEMATIC    EXAMINATION    OF    THE    EYE  101 

When  the  ophthalmoscope  is  2^/2  inches  from 
the  patient's  eye  it  will  be  in  focus  and  any 
opacity  in  the  cornea,  anterior  chamber  or  lens 
will  ap])ear  black,  because  they  are  opaque.  A 
scar  on  the  cornea  that  appears  white  by  direct 
inspection  will  appear  black  like  a  piece  of  steel 
when  seen  with  the  ()])hthalmoscope. 

Incipient  Cataract:  Beginning  opacities  of 
the  lens  can  l)e  readily  diagnosed  with  the 
()])hthalmoscope;  and,  if  the  diagnosis  can  be 
made  by  the  general  practitioner,  he  may  find 
the  cause  of  the  opacity  by  examination  of  the 
urine.  If  the  physician  can  make  a  diagnosis 
of  beginning  of  cataract,  he  can  often  treat  his 
patient  quite  intelligently  by  giving  attention  to 
his  general  condition. 

If  an  opacity  of  the  lens  is  found  in  a  person 
over  forty,  that  is  not  congenital  or  caused  by 
an  injury,,  the  probability  of  beginning  cataract 
will  be  strong  enough  to  warrant  an  examination 
of  the  urine.  If  the  urine  is  found  negative,  and 
the  vision  not  less  than  20  40  a  deep  sub-con- 
junctival  injection  of  20  drops  of  one  to  4000 
cyanide  of  mercury  is  indicated,  after  cocainizing 
and  injecting  20  drops  of  a  2%  solution  of 
cocain.  If  vision  is  less  than  20  ^40,  a  good  result 
cannot  be  expected. 

Fourth  Step:  The  examination  of  the  vitre- 
ous is  made  by  reflecting  the  light  into  the  eye 
from  the  o])lithahnosco])e  at  a  distance  of  two 
feet  from  the  eye  and  looking  into  the  illuminated 
eye  through  the  aperture,  or  +  8  D.  at  closer 
range.    The  patient  is  instructed  to  look  up,  then 


102    OPHTHALMOSCOPY,    RETINOSCOPY   AND    REFRACTION 

down,  right  and  left;  if  the  vitreous  is  diseased, 
black  opacities  may  be  seen  floating  in  it  and  a 
diagnosis  of  uveitis  will  be  made.  If  the  vitreous 
is  clear  the  next  step  in  the  systematic  examina- 
tion should  be  made. 

Fifth  Step  :  The  eye  has  now^  been  examined 
from  before  backwards  to  and  including  the  vit- 
reous. The  examination  of  the  fundus  should 
never  be  attempted  until  a  systematic  examina- 
tion has  been  made  of  every  structure  in  front 
of  the  retina.  If  this  rule  is  observed,  few  mis- 
takes in  diagnosis  of  what  is  to  follow  will  occur. 

The  observer  should  now  plsice  himself  in  the 
same  j^osition  relative  to  the  eye  as  was  described 
in  Figure  33;  and,  when  in  position,  should  in- 
struct his  patient  to  look  at  some  point  or  spot 
on  the  opposite  wall.  Tell  him  too,  that  3^ou 
will  not  obstruct  the  view  of  his  object,  and  that 
if  your  head  should  get  in  his  light,  he  must 
close  both  eyes  and  keep  them  closed  until  you 
tell  him  to  open  them. 

Red  Reflex:  The  mirror  of  the  ophthalmo- 
scope is  now  tilted  toward  the  light  which  is  re- 
flected into  the  eye  at  a  distance  of  about  two 
feet.  As  soon  as  the  student  reflects  the  light 
into  the  pupil,  the  red  glow  is  seen  and  he  ap- 
proaches the  eye  as  quickly  as  possible,  without 
allowing  the  light  to  get  out  of  tlie  ]:)U])il.  (Fig- 
ure 34.) 

White  Line:  The  student  while  approach- 
ing the  eye  and  through  the  examination,  keeps 
both  eyes  open.  If  the  eye  is  normal  or  em- 
metropic, the  white  lines  in  the  arteries  disappear 


SYSTEMATIC    EXAMINATION    OF    THE    EYE  103 

when  a  plus  k  ns  is  placed  behind  tlie  aperture 
of  the  ophthalmoscope.  If  the  white  lines  on  the 
arteries  are  seen  when  a  plus  lens  is  placed  behind 
the  aperture,  the  eye  is  hypermetro]3ic  and  the 
strongest  plus  glass  with  which  the  white  lines  can 
be  seen  at  all  indicates  the  hypermetropia. 

If  the  white  lines  on  the  arteries  cannot  be 
seen  when  looking  through  the  aperture  of  the 
ophthalmoscope  nor  when  plus  lenses  are  placed 
behind  it,  but  do  become  visible  when  minus 
lenses  are  used,  the  weakest  one  with  which  they 
can  be  seen  at  all  on  the  retinal  vessels  represents 
the  degree  of  myopia. 

Retinal  Vessels:  When  measuring  the  re- 
fraction of  the  eye,  the  character  of  the  retinal 
vessels  should  be  noted.  If  the  veins  are  normal 
and  the  arteries  are  small  and  threadlike,  there  is 
a  strong  suspicion  of  optic  atro])hv  and  the  field 
should  be  taken.     (See  Plate  XVllI.) 

If  the  retinal  vessels  are  twisted  or  tortuous,  a 
diagnosis  of  retinitis  will  be  made.  (See  Plate 
XXL) 

Nerve  Head:  If  the  nerve  head  is  higher  or 
more  hypermetro])ic  than  the  normal  ])art  of  the 
retina,  a  diagnosis  of  optic  neuritis  will  be  made. 
(See  Plate  XXI  and  XXII.) 

Optic  Xekve:  If  the  retinal  vessels  do  not 
a])pear  to  emerge  from  the  center  of  the  optic 
nerve  (Plates  I  and  II),  but  seem  to  disap- 
pear abruptly  at  the  edge  of  the  nerve  head,  a 
diagnosis  of  glaucoma  will  be  made.  (  See  Plate 
XXIII.)      However,  if  the  optic  nerve  appears 


104    OPHTHALMOSCOPY,    RETINOSCOPY   AND    REFRACTION 

wliite  or  gray,  (See  Plate  XVIII)  a  diagnosis 
of  atrophy  should  not  he  made,  until  the  fields  of 
both  ej^es  have  been  taken,  providing  the  patient 
has  enough  vision  in  either  eye  to  make  this  pos- 
sible. The  field  should  always  be  taken  in  all 
suspicious  cases. 

Pigment:  If  patches  of  wliite  or  spots  of 
black  are  seen  in  the  fundus,  their  position  should 
be  noted.  If  they  are  on  top  of  the  retinal 
vessels.  Plates  V  and  YI,  the  pigment  must  be 
in  the  retina,  but  if  the  vessels  are  on  top  of  the 
spots,  the  lesion  must  be  in  the  choroid.  (Plates 
XI  and  XII.) 

If  spots  are  found  on  the  temporal  side  of 
the  fundus,  "in  the  macular  region"  at  the  fovea 
centralis  and  the  patient  has  poor  vision  that 
cannot  be  made  normal  with  glasses,  a  diagnosis 
of  central  choroiditis  will  be  made.  (Plate  XIV 
and  XV.) 

Gross  lesions  and  changes  from  the  normal,  in 
the  shape  of  large  pigmented,  or  atrophic  spots 
often  appear  in  any  part  of  the  fundus  except 
the  temporal  side  without  affecting  central  vision. 

Color  of  Fundus  :  If  some  part  of  the  fundus 
is  observed  that  is  lighter  in  color  than  other 
parts  or  is  entirely  without  color,  the  normal  and 
abnormal  portion  should  be  refracted;  and,  if 
the  lighter  part  is  more  hypermetropic,  the  stu- 
dent knows  that  he  is  dealing  with  an  exudate, 
a  detachment  of  the  retina  or  a  growth. 

Media:  If  the  media  is  clear,  a  differential 
diagnosis  can  readil}^  be  made.     If  the  media  is 


SYSTEMATIC    P:XAML\ATIO-\    OF    THE    EYE  105 

not  clear  and  the  diagnosis  witli  the  oplithahno- 
scope  is  douhtful  the  tension  of  the  eye  will  he 
of  great  aid. 

If  the  eye  has  been  examined  in  the  manner 
described  and  a  diagnosis  cannot  he  made,  a  last 
hut  most  important  step  will  he  the  taking  of 
the  field  as  described  on  ])age  8(5. 

Blooj)  Pkessuke:  To  c()m])lete  the  examina- 
tion the  Systolic  and  Diastolic  blood  pressure 
should  be  taken,  the  urine  examined,  and  a 
microscopical  examination  of  the  conjunctival 
contents  made  if  necessary. 

Amblyopia:  It  is  only  justifiable  to  make  a 
diagnosis  of  amblyopia  if  a  diagnosis  of  some 
other  condition  cannot  be  made. 

After  the  student  has  made  enough  systematic 
examinations  to  have  the  different  steps  fairly 
fixed,  he  Avill  not  have  any  very  great  difficulty 
in  arriving  at  a  proper  diagnosis;  and  when  a 
diagnosis  has  been  made,  any  text  book  on  o])h- 
thalmology  will  give  the  ])ro])er  treatment. 

Diagnosis  in  ophthalmology  is  not  difficult  it 
approached  in  the  proper  manner,  but  it  would 
be  impossible  unless  the  student  were  master  of 
the  ophthalmoscope. 

TENSIO^' :  Before  taking  the  tension  of  any 
eye,  the  patient  should  be  requested  to  look 
down,  when  we  pal])ate  by  ])lacing  the  ti])s  of 
two  index  fingers  upon  the  u])])er  lid  and  gently 
press  down  as  though  palpating  for  pus  in  any 
part  of  the  body,  noting  the  (lifTerence,  if  any. 
in  the  tension  of  the  two  eyes.     (Figure  37.) 


106    OPHTHALMOSCOPY,    RETINOSCOPY    AND    REFRACTION 


Fig.    37.     Testing    Tension    of    the    Eyeball 

Taking  the  tension  with  the  fingers  usually 
suffices  when  the  eye  is  very  soft  or  hard,  hut  if 
a  suspicion  of  an  increase  of  tension  exists,  the 
tonometer  should  be  used. 

The  use  of  the  tonometer  requires  delicate 
technique;  it  need  not  be  confined  to  an  expert, 
but  with  a  little  practice  can  be  of  value  in  the 
hands  of  any  general  practitioner. 

Before  using  the  tonometer,  the  eye  must  be 
anesthetized  by  dropping  3  or  4  drops  of  a  1% 
solution  of  holocain  hydrochlorate  into  it.  Three 
minutes  after  the  medicine  has  been  instilled  the 
patient  is  placed  upon  tlie  table  and  instructed 
to  look  at  the  ceiling  with  both  eyes. 


SYSTEMATIC    EXAMIMATION    OF    THE    EYE  107 

The  lids  are  kept  apart  with  the  fingers,  or 
with  Fisher's  lid  hooks.  (  Figures  :31)  and  40.)  The 
tonometer  is  ])laced  exactly  ii]3on  the  center  ol 
the  cornea,  held  straight  n]),  and  the  tension  of  the 
eye  can  he  read  from  the  scale  on  top  of  the 
instrument.  (Figure  38.)  The  tension  should 
he  taken  with  one  weight,  then  registered,  and 
with  two  weights  and  registered,  then  taken  again 
wdth  three  w  eights.  The  three  readings  should  he 
the  same  if  the  instrument  has  heen  ])ro])erlv 
used.  If  the  tonometer  registers  ahove  28,  the 
tension  is  supposed  to  he  above  normal.  After 
the  three  readings  are  registered  they  may  be 
added  and  divided  by  three  to  get  an  average. 

The  student  is  again  reminded  that  the  tension 
is  only  one  symptom  and  the  vision  and  especially 
the  field  should  always  be  studied  in  connnection 
with  glaucoma. 


108    OPHTHALMOSCOPY,    RETINOSCOPY    AND    REFRACTION 


TEST  BLOCK  fcg^ 

Fifr.    38.     Tonometer 


Fig.    40.     Fishev's    Lower    Lid    Hook 


SYSTEMATIC    EXA 


MINATIO-N    OF    THE    EYE  109 


Fig.    41.     Tonometei-  and    Patient 


110    OPHTHALMOSCOPY.    RETINOSCOPY    AND    REFRACTION 


CHAPTER  YII 

GLAUCOMA 

The  general  practitioner  can  give  liis  glaucoma 
])atients  proper  treatment  providing  he  can  make 
a  diagnosis;  but  a  diagnosis  is  often  impossible 
without  a  working  knowledge  of  the  ophthalmo- 
scope. 

The  symptoms  of  glaucoma  are  unlike  those 
of  any  other  disease  and  they  are  usually  so  well 
marked  that  a  diagnosis  is  within  the  grasp  of  the 
general  practitioner. 

If  a  systematic  examination  of  the  eye  is  made 
(see  Page  97)  it  will  not  be  difficult  to  make  a 
diagnosis  of  glaucoma  if  it  exists;  and  all  that 
appears  necessary  to  enable  the  general  ])racti- 
tioner  to  make  sucli  a  diagnosis,  is  to  have  an 
ophthalmoscope,  a  perimeter,  and  a  tonometer 
and  to  know  liow  to  use  them. 


GLAUCOMA  HI 

Clinically,  glaucoma  is  a  sini])le  proposition, 
l)ut  scientifically  much  is  to  be  learned.  The 
subject  will  be  treated  clinically  in  the  hope  that 
general  practitioners  will  be  able  to  make  a  diag- 
nosis. Only  two  varieties  of  glaucoma  need  be 
mentioned,  glaucoma  which  is  the  result  of  some 
unknown  cause;  and  glaucoma  which  is  caused  i)y 
some  known  disease,  injury,  or  operation  upon 
the  eye  ball. 

Sy3IPTo:ms:  A  patient  usually  over  forty, 
complaining  of  some  loss  of  vision,  pain  in  the 
eyes  or  head,  observing  a  picture  of  a  rainbow 
around  the  light,  should  be  looked  u])on  as  a 
possible  case  of  glaucoma. 

At  this  ])articular  ])oint  the  author  believes 
it  desirable  to  simplify  the  subject  by  omitting 
tlie  word  glaucoma  and  substituting  the  words 
"Plus  tension."  Anv  eye  that  has  tension  above 
normal  is  glaucomatous:  and  when  tlie  tension 
is  above  normal,  it  must  be  reduced  in  some 
manner  because  of  the  danger  of  loss  of  vision. 

Cause  of  Plus  Texsiox:  Injuries  to  the  eye 
or  operations  upon  tlie  eye  ball  and  intlamniation 
of  the  eye  causing  adhesions  of  the  iris  to  the 
lens  cause  many  eyes  to  become  hard,  or  have 
|)lus  tension:  but  plus  tension  may  appear  and 
destroy  the  eye  without  any  known  cause. 

Examination  of  the  eye  from  before  backward 
in  a  typical  case  would  be  as  follows: 

Plus  Tension  :  Cornea  anesthetic  and  hazy : 
anterior  chamber  shallow:  acqueous,  cloudy,  iris 
muddy:  pupil  dilated:  lens  clear:  vitreous  clear; 
pulsating  retinal  arteries;  nerve  head  cupped. 


112    OPHTHALMOSCOPY,    RETLNOSCOPY    AND    REFRACTION 

(See  Plates  XXIIl  and  Figure  16.)  Field 
contracted  below  and  to  the  nasal  side.  (Figure 
•24.) 

All  of  these  symptoms  need  not  be  found,  but 
enough  of  tliem  to  establish  a  diagnosis  can  usu- 
ally be  found  in  glaucoma. 

If  the  student  is  doubtful  about  any  increase 
in  tension  such  as  is  usually  determined  by  the 
fingers,  (Figure  37)  he  can  measure  the  tension 
with  tlie  tonometer  which  is  more  dependable,  es- 
pecially to  the  inexperienced,  in  taking  the  ten- 
sion (Figure  38)  ;  and,  if  still  in  doubt,  the  field 
can  be  taken  with  tlie  perimeter  which  is  all  im- 
portant and  does  not  require  an  expert. 

If  all  these  precautions  are  taken  in  doubtful 
cases,  the  medical  men  would  not  make  many 
errors  in  diagnosing.  AVhen  the  condition  has 
been  diagnosed  in  the  eye  com])lained  of,  taking 
the  tension  and  field  of  the  other  eye  is  impera- 
tive. The  ])rompt  institution  of  treatment  in 
this  inci])ient  stage  often  arrests  the  progress  of 
the  disease. 

Prognosis:  The  prognosis  will  depend  u])ou 
the  cause,  being  grave,  in  those  that  have  no 
known  causation,  as  in  Plate  XXIII  and 
XXIV,  but  guarded  in  all  cases. 

Treatment:  In  those  that  have  plus  tension 
from  injuries  to  or  operations  upon  the  eye  ball, 
or  inflammations  that  have  caused  adhesions  of 
the  iris  to  the  lens,  atropin  sulphate  is  indicated, 
using  two  drops  of  a  l^  solution  dropped  into 
the  eve  three  times  a  dav;  alwavs  instructing  the 


GLAUCOMA  113 

])atient  to  press  upon  the  tear  duct  for  a  iiiiuute 
after  putting  in  tlie  drops. 

In  those  that  have  pkis  tension  from  some  un- 
known cause,  the  treatment  is  quite  simple  and 
consists  of  a  sohition  of  eserin  salicyhite  to  be 
dropped  into  the  eye  instead  of  atropin. 

As  soon  as  the  eye  is  found  to  liave  tension 
above  the  normal  without  a  known  cause  for  the 
condition,  two  drops  of  freshly  ])repared  and 
sterile  sohition  of  sahcylate  of  eserin  should  be 
instilled  into  the  eye  every  three  hours  day  and 
night.  The  medicine  needs  to  be  continued 
throughout  the  entire  twenty-four  hours  because 
the  effect  of  eserin  lasts  only  about  three  hours. 

It  is  often  best  to  begin  with  a  solution  of 
V2  gi'ain  to  the  ounce.  If  the  tension  is  reduced 
to  normal  with  this  weak  solution,  it  can  be  kept 
up  indefinitely;  or  a  solution  of  nitrate  of  pilo- 
carpin,  "Posey"  can  be  substituted  for  the  eserin 
to  be  used  during  the  day  with  eserin  at  night. 
If  the  weak  solution  does  not  have  any  effect 
upon  the  tension  after  three  instillations,  the 
strength  should  be  made  one  grain  to  the  ounce. 
If  this  strength  does  not  suffice  with  three  instilla- 
tions, a  still  further  hicrease  can  be  made  up  to 
four  strains  to  the  ounce  unless  it  causes  severe 
pain.  Eserin  and  Pilocarpin  are  both  used  at 
the  same  time  by  some  with  good  effect. 

Some  insist  upon  the  patient  being  in  bed  while 
the  myotic  is  being  used.  A  general  examination 
should  be  made  in  an  endeavor  to  locate  the  cause 
which  should  include  the  examination  of  the  urine, 
blood,  mouth,  throat,  nose  and  intestinal  canal 


114    OPHTHALMOSCOPY,    RETINOSCOPY   AND    REFRACTION 

with  an  X-Ray  of  the  teeth,  and  snch  genera] 
treatment  as  is  indicated,  including  ehminatives 
especially  (an  enema  should  be  given  every 
night).  If  the  tension  is  not  reduced,  operative 
procedure  should  not  be  delayed. 

Atropin  and  Eserix:  The  student  is  cau- 
tioned regarding  atropin  and  eserin.  Eserin  is 
used  in  all  cases  tchere  the  eye  has  plus  tension 
mthout  a  knotcn  cause,  and  atropin  after  in- 
juries to  the  eye,  after  operation  upon  the  e^^e 
ball,  and  tchen  the  eye  has  plus  tension  from  in- 
flammation where  the  iris  is  adherent  to  the  lens. 

The  student  will  see  by  the  foregoing  that 
eserin  and  atropin  have  their  distinctive  places. 
It  is  not  often  that  a  mistake  is  made — because  of 
the  exact  indications  for  the  use  of  each. 

Operative  Treatment:  When  an  eye  is  in- 
jured, the  lens  may  become  opaque.  "Traumatic 
Cataract,"  produces  swelling;  and,  in  patients 
over  twenty,  it  is  often  necessary  to  remove  the 
lens.  In  such  cases,  atropin  or  eserin  would  not 
suffice  because  the  swollen  lens  would  be  the 
cause  of  the  plus  tension  and  its  removal  would 
be  the  only  rational  method  of  reducing  it. 

Occluded  Pupil:  Adhesions  of  the  iris  to 
the  lens  resulting  from  inflammation  of  the  eye 
sometimes  prevent  the  aqueous  from  passing 
from  the  anterior  to  the  posterior  chamber  and 
may  be  so  firm  that  they  cannot  be  broken  by 
the  use  of  atropin.  They  may  thus  be  the  cause 
of  the  increased  tension. 

In  such  a  case  an  iridectomy  should  be  done 
upward  to  reduce  the  tension  without  disfiguring 


GLAUCOMA  115 

the  eye,  si  nee  the  iridectomy  would  be  covered  by 
the  lid.  It  is  not  necessary  to  make  a  deep 
iridectomy  for  this  purpose  as  must  be  done  for 
reducing  tension  with  an  unknown  cause. 

Pakacentesls  :  A  cataract  knife  is  passed  into 
the  anterior  chamber,  turned  slightly  upon  its 
edge,  tlie  anterior  chamber  slowly  evacuated,  the 
knife  carefully  withdrawn,  and  the  eye  bandaged. 
Various  operative  procedures  have  been  devised 
for  reducing  the  tension  when  the  cause  is  not 
known  but  commonly  called  glaucoma;  a  prop- 
erly performed  iridectomy  has  produced  the  best 
results  in  the  author's  hands  and  the  Smith 
method  has  been  unusuallv  satisfactorv. 


116    OPHTHALMOSCOPY,    RETI.NOSCOPY    AND    REFRACTION 

CHAPTER  VIII 

OPTICAL  PRINCIPLES,   TEST   TYPE, 

LENSES,   REFRACTION    AND 

CYLOPEGICS 

Eacli  of  the  various  methods  of  diagnosis 
of  refractive  errors  is  some  apphcation  of  the 
use  of  lenses;  and  the  placing  of  them  before 
the  defective  eye  for  more  or  less  constant  wear 
is  the  only  means  we  have  for  their  correction. 
It  is  therefore  necessary  to  try  to  make  clear  the 
theory  of  their  action,  and  their  application  for 
these  purposes. 

Light:  Light  or  radiant  energy  is  given  off 
from  all  luminous  objects,  its  greatest  source  of 
course  being  the  sun.  It  is  transmitted  by  wave 
action  in  the  universal  ether  at  the  enormous 
speed  of  nearly  two  hundred  thousand  miles  per 
second  through  empty  space  where  it  meets  with 
no  resistance.  As  it  approaches  the  earth,  how- 
ever, its  speed  is  slightly  reduced  by  tlie  inter- 
ference offered  by  our  atmosphere  and  more  so 
by  other  objects  of  greater  density  with  which 
it  comes  in  contact,  and  which,  if  at  all  pigmented, 
absorb  a  greater  or  less  quantity  of  the  light  as 
it  passes  through  or  enters  into  them.  The  whole 
theory  of  the  action  of  lenses  rests  on  the  above 
phenomena. 

Laws  or  Lens  Action:  In  taking  up  the 
study  of  the  action  of  lenses,  tlie  student  must 
accept  the  following  two  laws : 


OPTICAL    PRINCIPLES  117 

1.  A  ray  of  litilit  entering  and  leaving"  a  re- 
fracting medium  ])eri)en(licular  (or  noi'inal  as  it 
is  called  in  optical  nomenclature)  to  its  surface, 
is  not  refracted  but  continues  with  its  direction 
unchanged.  Such  a  ray  is  spoken  of  as  the  axial 
ray. 

2.  A  ray  of  light  entering  a  denser  from  a 
rarer  refracting  medium  is  deviated  toward  the 
])erpendicular  to  the  entered  surface;  and  leaving 
a  denser  to  reenter  a  rarer  medium,  is  refracted 
away  from  the  perpendicular  to  the  surface  last 
passed  through.  Practically,  however,  in  our 
work  the  net  result  of  this  double  refraction  is 
a  deviation  of  the  refracted  ray  toward  the 
thicker  portion  of  the  denser  refracting  medium. 

Pkoductiox  of  Images:  The  next  point  in 
our  study  of  lens  action  is  the  consideration  of 
the  phenomena  of  the  production  of  images  which 
is  really  only  an  application  of  the  two  above 
laws,  differing  from  the  latter  only  in  the  fact 
of  considering  the  action  of  all  the  incident  rays 
instead  of  only  a  few. 

Action  of  Convex  Lenses:  If,  in  the  case 
of  the  convex  lens,  (Figure  42)  instead  of  only 
one  or  two  incident  rays,  we  consider  tlie  action 
of  all  the  I'ays  that  enter,  we  can  readily  see  that 
we  must  have  such  a  result  as  is  illustrated  in 
Figure  42,  in  which  all  the  incident  rays  are 
shown  converging  and  tinally  coming  to  a  point 
of  focus  after  passing  tlirough  the  lens. 

This  is  not  a  matter  of  theory,  but  can  be  shown 
experimentally  with  any  suitable  source  of  illumi- 


118    OPHTHALMOSCOPY,    RETIXOSCOPY    AND    REFRACTION 

nation  and  a  screen  placed  at  the  ])roper  distance 
irom  the  lens. 

When  the  source  of  illumination  is  placed 
twenty  feet  or  farther  away,  usually  spoken  of  as 
infinity  from  the  lens,  the  rays  that  leave  it  and 
enter  the  latter,  do  so  practically  parallel  to  each 
other;  and,  in  order  to  secure  a  distant  image, 
which  will  he  inverted,  of  the  source  of  illumina- 
tion, the  screen  must  be  placed  at  a  certain  defi- 
nite distance  from  the  center  of  the  lens.  This 
point  is  called  the  principal  focus  of  the  lens  and 
its  distance  from  the  center  of  the  latter  is  the 
focal  length.  This  last  is  made  use  of  in  com- 
puting the  dioptric  or  refractive  strength  of  the 
lens  as  described  on  page  127.  Since  the  image 
in  this  case  can  be  demonstrated  as  described 
above,  it  is  spoken  of  as  a  positive  or  real  image, 
and  the  point  at  wliich  it  occurs  as  a  positive  or 
real  focus. 


Fig.    42.      The   Action    of    a    Convex        Fig.    43.      The   Action   of   a   Concave 
Lens   on    Parallel   Rays.      (May.)  Lens  on  Parallel  Rays.      (May.) 

AcTiox  OF  Concave  Lenses:  Figure  48. 
When  we  apply  the  above  principles  to  the  con- 
cave lens,  we  secure  the  very  different  result  illus- 
trated in  Figure  43. 

The  parallel  rays  entering  the  lens  are  caused 
to  diverge  and  obviously  can  never  come  to  a 


OPTICAL    PRINCIPLES 


119 


focus.  However,  if  we  place  one  eye  in  the  path 
of  these  divergent  rays,  we  are  able  to  observe 
an  erect  reduced  image  of  the  source  of  illumina- 
tion which  is  the  result  of  the  prolonging  back- 
ward of  the  refracted  divergent  rays  shown  by 
the  dotted  lines  in  Figure  43;  this  image  is 
located  at  the  priiici])al  focus  of  the  lens.  Such 
an  image  which  cannot  be  thrown  on  a  screen 
and  can  be  observed  only  through  the  concave 
lens  producing  it,  is  spoken  of  as  a  virtual  image. 
Conjugate  Foci  :  Another,  but  minor  matter 
to  be  considered  in  studying  the  action  of  convex 
lenses  is  that  of  conjugate  foci,   (Figure  44)   in 


Fig     44.      ConjuKate    Fc 


of 


Convex    Lens.       (May.) 


Which  the  source  of  illumination  being  less  than 
twenty  feet  away,  the  incident  rays  enter  the  lens 
not  parallel  to  each  other  but  decidedly  diverging. 
Obviously  they  will  not  be  brought  to  a  focus  at 
a  point  as  near  the  lens  as  they  would  if  they 
had  entered  the  latter  parallel  to  each  other. 

In  sucli  a  case,  the  source  of  illumination  and 
its  image  beyond  tlie  lens  are  s])oken  of  as  con- 
jugate foci,  and  are  interchangeable  and  capable 
of  being  located  at  any  point  between  the  princi- 
pal focus  of  the  lens  and  twenty  feet. 

The  Spectru:m  :    There  is,  however,  one  strik 


120    OPHTHALMOSCOPY,    RETINOSCOPY    AND    REFRACTION 

ing  phenomena  that  oceurs  when  performing  the 
above  experiment  which  the  student  shonld  un- 
derstand. If  a  suitable  screen  (a  prism)  be  pro- 
vided on  whicli  the  emergent  rays  are  allowed  to 
fall,  instead  of  a  colorless  illumination  of  it  oc- 
curring, such  as  happened  when  the  convex  and 
concave  lenses  were  used,  there  will  be  a  beautiful 
display  of  colors  always  in  a  definite  order — red, 
orange,  yellow,  green,  blue,  indigo  and  violet, 
reading  from  the  apex  toward  the  base  of  the 
prism.  These  colors  in  tliis  order  are  spoken  of 
as  the  primary  colors  of  the  SOLAR  SPEC- 
TRUM. 

Concave  and  Convex  Lenses  as  Prisms  :  The 
above   ])henomena   occur   in   a    modified   degree 


Fig.     45.        Formation 

of  Lenses   by  Prisms. 

(May.) 


Fig.     46.       Convex 
Lenses.    1,  Piano-Con- 
vex ;  2,   Bi-Convex  ;   3, 
Convex  meniscus. 
(May.) 


Fig.  47.  Concave 
Lenses.  1,  Plano-Con- 
Concave ;  2,  Bi-Con- 
cave  ;  3,  Concave  me- 
niscus.    (May.) 


when  strong  convex  or  concave  lenses  are  used, 
since,  as  shown  by  Figure  4.5,  they  may  quite 
properly  be  regarded  as  collections  of  prisms  with 
their  bases  toward  the  center  or  periphery  of  the 
lens  as  the  case  may  be. 

The  last  point  is  aptly  illustrated  by  the  cus- 
tomarily used  rapid  method  for  determining  the 
character    of    an   unknown   lens,    looking   at    a 


OPTICAL    PRINCIPLKS 


121 


distant  object  through  it  wliile  moving  the  lens 
slight!}'  from  side  to  side,  when  it  will  be  noted 
that  the  object  looked  at  seems  to  move  in  the 
direction  opposite  to  that  taken  by  the  lens  if 
it  be  convex  and  in  the  same  direction  if  it  be 


concave. 


1 

Fig.      48.       Refraction     by     Convex 
Cylindric    Lens.       (Ball.) 


Fig.     49.       Refraction     by     Concave 
Cylindric    Lens.       (Ball.) 


CviJNDRTCAi.  Lenses:  There  remains  yet  an- 
other form  of  lens  to  consider,  which,  from  its 
shape,  is  called  the  cylindrical  lens  and  which  may 
be  either  convex  or  concave.  It  differs  in  shape 
from  the  other  forms  in,  that  in  one  direction  or 
axis  of  the  lens,  as  it  is  called,  there  is  absolutely 
no  curvature  and  hence,  rays  entering  in  this 
region  undergo  no  refraction. 

On  leaving  the  axis,  however,  a  curvature  be- 


122    OPHTHALMOSCOPY,    RETINOSCOPY    AND    REFRACTION 

gins  and  gradually  increases  until,  in  the  meridian 
at  right  angles  to  the  axis,  it  reaches  a  maximum 
and  rays  passing  through  it  are  markedly  re- 
fracted. 

As  stated  above  this  lens  may  be  either  convex 
or  concave,  and  the  phenomena  of  image  produc- 
tion occurs  in  precisely  the  same  way  as  previ- 
ously described  save  that,  instead  of  a  focal  point, 
a  focal  line  is  produced  which  always  extends  in 
the  same  direction  as  does  the  axis  of  the  lens. 

Action  of  Lenses  in  Practice  :  In  the  above 
discussion  of  the  action  of  lenses,  which  will 
not  be  referred  to  again  but  which  must  be  thor- 
oughly understood  by  the  student  for  the  purpose 
of  emphasis  and  other  reasons,  much  has  been 
said  about  the  focus,  the  focal  distance,  etc.  In 
actual  practice,  however,  in  either  diagnosis  or 
treatment  actual  images  are  never  produced  and 
incident  rays  are  never  brought  to  a  focus  save 
in  the  applications  of  indirect  ophthalmoscopy. 
Lenses  are  used  rather,  even  on  eyes  from  which 
the  crystalline  lens  has  been  removed,  to  modify 
the  incident  rays  only  in  an  amoimt  equal  to  the 
deficiency  of  the  eye  under  examination  or  treat- 
ment, leaving  the  final  focus  and  image  to  be 
produced  bv  tlie  refractive  svstem  of  the  eve 
itself. 

Lens  Material:  A  careful  consideration  of 
the  above  Avill  make  it  clear  that  any  transparent 
object  with  variously  shaped  surfaces  may  act 
in  the  capacity  of  a  lens.  It  having  been  found 
that  air  having  a  refractive  strength  only  slightly 
in  excess  of  a  vacuum,  it  has  been  taken  as  a 


OPTICAL    PRINCIPLES  123 

standard  and  ex]jeriments  have  ])een  ])erfornied 
with  many  different  suhstances  to  determine  their 
refractive  powers  as  compared  with  that  of  air, 
the  results  being  recorded  as  indices  of  refraction. 
Those  of  the  commoner  ones  and  of  the  refractive 
mediae  of  the  eye  are  given  in  the  following  table: 

IXDIC  ES  OF  REFKACTIOX 

Air 1.00 

Water 1 .33 

CroAvn  glass 1  ..5 

Flint  glass l.,58 

Diamond 2  A 

Cornea    1.33 

Aqueous  humor 1.3 

Crystalline  lens 1.41 

Vitreous  liumor 1.3.5 

It  is  obvious  that  of  the  above  substances,  glass 
is  the  only  one  that  can  be  made  use  of  on  a 
conmiercial  scale  for  the  manufacture  of  lenses: 
and,  of  the  two  forms,  crown  glass  has  been  found 
to  be  preferable.  Flint  glass  is  made  use  of  only 
and  in  combination  Avith  crown  glass  in  the  manu- 
facture of  optical  instruments  in  which  s])herical 
aberration  must  be  overcome,  and  f(^r  making 
certain  forms  of  bifocal  lenses. 

Test  Lens  and  Tkiai-  Fi?a:mk:  Crown  glass 
as  noted  above  has  been  found  to  liave  certain 
advantages  over  Hint  that  liave  resulted  in  its 
coming  into  general  use.  In  addition  to  its  use 
in  the  various  otiier  instruments,  it  is  made  up  in 
sets  of  pairs  of  convex  and  concave  s])]ieres  and 


124    OPHTHALMOSCOPY,    RETINOSCOPY    AND    REFRACTION 

convex  and  concave  cylinders  varying  in  refrac- 
tive strength  by  suitable  intervals  from  the 
weakest  lens  used  to  as  strong  as  is  usually  re- 
quired, mounted  in  circular  frame  in  the  handle 
of  which  is  cut  a  plus  or  minus  sign  to  indicate 
the  character  of  the  contained  lens,  and  on  which 
is  also  stamped  its  dioptric  value,  of  one  and  one- 
half  inch,  or  one  and  one-fourth  inch,  of  which 
the  former  has  been  found  to  be  the  ])referable. 


Fig.    50.     Trial    Frame 


The  trial  frame  should  have  a  quadrant  at- 
tached to  each  cell  which  shoidd  be  capable  of 
various  adjustments  in  order  that  the  lenses  may 
be  properly  centered  before  the  eyes  and  that  it 
with  its  weight,  which  is  necessarily  considerable, 
may  be  comfortably  worn.     (See  Figure  50.) 

Various  substitutes  have  been  devised  to  over- 
come the  objection  to  the  weight  of  the  trial 
frame,  which  occasions  considerable  difficulty. 

Cyhndrical  lenses  are  further  distinguished  by 
having  a  short  line  etched  at  tlie  extremities  of 
the  meridian  of  the  axis,  and  sometimes  in  addi- 


OPTICA  I.    PRINCIPLES 


125 


FiK.    r.l.      Maddux    Rod 

tion  to  the  above  a  frosting-  of  the  borders  of  the 
lens  parallel  to  the  axis.  Some  operators  prefer 
a  further  general  differentiation  between  tlie  plus 
and  minus  lenses  having  the  frames  of  the  two 
forms  made  of  different  materials,  as  for  instance, 
ahiminic  for  tlie  ])his  and  gold  phited  for  the 
minus. 


126    OPHTHALMOSCOPY.    RETINOSCOPY    AND    REFRACTION 

Accessories  and  Pris:ms:  In  addition  to  the 
spheres  and  cyhnders  described  above  certain 
accessory  discs,  the  uses  of  which  will  be  discussed 
later,  are  provided,  as  well  as  a  set  of  prisms  with 
their  strengths  usually  expressed  in  prism  diop- 
tres stamped  on  the  handle. 

A  prism  dioptre  is  described  as  the  amount  of 
prismatic  effect  produced  by  decentering  a  one 
dioptre  sphere  one  centimeter  in  any  direction  or 
a  one  dioptre  cylinder  a  similar  distance  in  the 
direction  at  right  angles  to  its  axis. 


Fig.    55.     Ti-ial    Case 


The  Trial  Case:  For  convenience  sake  all 
of  the  above  are  collected  in  sets  and  kept  in 
suitable  containers  w^hich  are  made  in  various 
forms  to  suit  the  needs  of  the  operator;  of  these 
the  most  common  form  is  shown  in  figure  55  and 
the  whole  collection  with  the  containers  is  known 
as  the  trial  case. 

In  determining  the  refractive  condition  of  an 
eye  by  the  so  called  subjective  method,  the  patient 
w^th  the  trial  frame  properly  adjusted  looks  at 


OPTICAL    PRINCIPLES  127 

some  object  selected  by  the  operator  and  reports 
to  the  latter  the  effects  on  vision  produced  by  the 
introduction  into  the  trial  frame  of  various  lenses 
or  accessories  from  the  trial  case,  the  successive 
changes  being  determined  by  the  effects  pro- 
duced. With  the  many  workers  in  the  same  field 
it  has,  of  course,  been  found  desirable  to  have  a 
standard  of  tests  objects,  as  they  are  called.  For 
distant  testing,  Snellen's  test  type  with  its  vari- 
ous adaptions  for  the  examination  of  illiterates  is 
the  one  used.  As  was  stated  in  the  discussion  of 
lens  action,  after  having  traveled  a  distance  of 
twenty  feet  from  their  source  or  origin,  rays  of 
light  are  practically  ])arallel.  For  accurate  work 
this  distance  should  be  maintained  either  actually 
or  by  the  use  of  a  reversed  chart  and  a  mirror 
between  the  ])atient  and  the  test  type,  in  all  dis- 
tant subjective  examination. 

Snellen's  Test  Types:  The  final  application 
of  the  Snellen  principle  is  the  production  of  a 
chart  such  as  is  shown  in  Figures  06,  .57  and  .58, 
consisting  of  letters  of  such  different  sizes  that, 
conforming  to  the  above  principle  and  wlien  well 
illuminated,  tlie  various  lines  should  be  read  by 
the  individual  with  normal  vision  at  distances 
ranging  from  ten  to  two  hundred  feet. 

The  Illiterate  Chart:  Various  modifica- 
tions of  this  chart  have  been  devised  but  the 
most  useful  one  and  the  only  other  one  the 
operator  need  have  is  the  "E"  chart,  (Figure 
57)  for  use  with  those  who  do  not  read  Englisli 
and  for  children  who  when  provided  with  the 
metal    "E,"     (Figure    59)    become    very    much 


128    OPHTHALMOSCOPY,    RETINOSCOPY    .AND    REFRACTION 


Jfc, 

E  . 

a 

F   P-2 

■E  , 

s  q;  n 

-T  O  Z-3 

n  E  2 

e-S  0  T- 

-  p  E  c  r  D?:  5 

3  u  m  3 

S  :-a  1  0  a  <i  - 

•*B  D  r  C  Z  P-.:  6 

vE  U  E  3    4 

8  :..«i  s  0  1  a  a- 

•«.    r  fi  t  0  P  Z  0  m;  7 

-    n  3 '3  "u  y      5 

V  -.M  a  s  1  0  J  3  1   -. 

ssrroTzo    <jO 

-     3 Eu 3 rt y       6 

.    .3-;;.,     7 

0«>     oaToiTota 

^     .   .   ,   0   »   ,   0  ,     .^.   9 

G  .^.     .  0  ,  a  0  ,  ,  .    .„ 

-.        r  .  ,  .  T  .  .  .         y  10 

^          ,..11 

0L_.    ,,,,.,,,    ^„ 

rr._,    

F:g.   56.     Snellen    Test         Fig.  57.     Snellen  Test  Fig.  58.     Snellen  Test 

Type.  Type — Illiterate.  Type  —  Reversed     for 

Mirror. 

interested  in  indicating  the  letters  called  to  their 
attention  giving  more  accurate  answers  than 
when  one  of  the  numerous  toy  charts  are  used. 

Special  Charts:  Some  operators  claim  there 
is  an  advantage  in  having  the  colors  reversed, 
that  is  white  letters  on  a  black  background,  and 
a  recent  investigator  has  presented  evidence  to 
show  that  red  letters  on  a  white  background  give 
more  accurate  results. 

The  Reversed  Chart:  Should  it  happen 
that  the  operator  is  working  in  an  office  of  con- 


OPTICAL    PKIXCIPLES 


129 


Fig.    59.     Metal    "E"    with    Handle 


siderably  less  tlian  twenty  feet  length,  he  will 
need  to  make  use  of  a  reversed  Snellen  chart. 
(Figure  .58)  hung  in  a  good  light  above  the 
patient's  head  and  a  mirror  placed  ten  feet  away 
whicli  doubles  the  distance.  If  this  distance  does 
not  corres])ond  with  the  end  of  the  room,  the 
mirror  may  be  hung  on  a  bracket  so  tliat  it  may 
be  swung  out  into  ])osition  as  needed  and  back 
against  the  wall  wlien  not  in  use.  With  this 
arrangement,  one  can  ])oint  out  letters  on  the 
chart  without  leaving  the  patient's  side — really 
a  great  convenience. 

Testing  and  Kkcording  Visuai,  x\cuity: 
Of  course,  no  operatoi-  refracts  patients  with  the 
chart  of  a  distance  of  two  hundred  feet,  but  it 
is  found  convenient  to  have  type  that  should  be 
read  up  to  that  distance  as  a  means  of  recording 


130    OPHTHALMOSCOPY,    RETINOSCOPY   AND    REFRACTION 

visual  acuity.  Thus,  if  when  seated  at  a  distance 
of  twenty  feet  from  the  chart  the  patient  reads 
the  hues  that  should  be  read  at  that  distance,  his 
visual  acuity  is  described  as  20/20  or  normal. 
Xot  infrequently  persons  are  met  with  who 
have  better  than  the  normal  visual  acuity — 20/15 
or  even  20/10,  while  in  practice  we  constantly 
meet  people  with  a  vision  of  20/200  or  even  less, 
in  which  last  event  we  bring  the  chart  nearer  the 
patient  until  the  largest  type  can  be  read,  when 
we  record  his  vision  with  a  fraction  making  two 
hundred  the  denominator,  and  the  distance  at 
which  the  largest  type  was  read  the  numerator; 
as  for  instance,  if  he  read  the  20/200  line  at  8  feet 
we  record  his  vision  8/200.  In  cases  of  very  low 
acuity  of  vision,  we  note  the  distance  at  which 
the  patient  can  count  the  operator's  fingers  in 
a  good  light  and  against  a  dark  background,  re- 
cording the  result  as  "counts  fingers  at  three  feet" 
or  3/200,  when  still  further  reduced,  we  record 
the  vision  as  "has  perception  and  projection," 
and  no  vision  being  present,  "has  no  perception 
or  projection,"  perception  meaning  simply  sen- 
sitiveness to  light  and  projection  the  ability  to 
determine  from  what  direction  it  comes. 

Jaeger's  Test  Type  : .  For  testing  and  record- 
ing the  near  vision  and  in  its  correction  when 
necessary  Jaeger's  test  type,  which  consists  of 
different  sizes  of  ordinary  Roman  types  arranged 
in  order  of  size  and  numbered,  beginning  Avitli 
the  finest  as  Jaeger  one  (abbreviated  J.  1.  etc.) 
Figure  60  is  used. 


OPTICAL    PRINCIPLES 


131 


which  he  Mrved.    Both  ntasei 
Ihe  crown,  althoueh   each,   perhaps, 
the  sequel,  a  Bata> 


been  the   inevitable 


for  Classiciu  was  but  the 
prototype  of  Anjou,  u 
Brinno  of  Brederode,  and 
neither  was  destined,  in 
this  world,  to  see  his  sacri- 
fices   cro^roed    with    success. 


Fig.    60,     Jaeger  Test   Type 


Fig.    61.     Astigmatic    Chart 


Of  recent  years,  a  new  system  of  nuniberint^ 
the  Jae<>'er  type  lias  come  into  use,  the  apphca- 
tion  of  which  will  he  (hscussed  under  presbyopia. 

The  xVsTiGMATic  Chart:  In  addition  to  the 
above  charts  anotlier,  tlie  so-called  astigmatic 
chart,  has  been  devised  of  which  many  forms  are 
in  use,  the  commonest  one  perhaps  hein^-  illus- 
trated in  FioTire  61. 

While  some  operatoi's  consider  its  use  indis- 
])ensable  in  the  coi'rectiou  of  astioniatism.  others 
prefei'  to  dis])eiisc  with  it  and  to  (le])end  on  visual 
results,  as  determined  with  the  Snellen  type, 
alone  in  their  work  with  the  trial  case. 


132    OPHTHALMOSCOPY,    RETINOSCOPY    AND    REFRACTION 

The  Use  of  the  Trial  Case:  When  one  is 
familiar  witli  lenses  and  their  action,  he  is  ready 
to  consider  their  application  in  the  diagnosis  of 
refractive  errors.  The  nse  of  the  trial  case  and 
the  test  charts  for  this  pm-pose  is  often  spoken  of 
as  manifesting  or  taking  the  manifest  since  it  is 
most  frequently  done  without  the  ciliary  muscle 
having  been  put  at  rest.  If  this  latter  has  been 
done,  we  speak  of  refracting  under  a  cyclopegic 
or  taking  the  static  refraction  subjectively. 

Rules:  In  either  event,  accurate  results  are 
dependent  upon  a  systematic  use  of  the  test 
lenses  and  accessories,  the  rules  for  which  must 
be  learned  and  followed,  and  which  will  now  be 
set  forth: 

1st.  The  patient  must  be  comfortably  seated 
twenty  feet  from  the  well-illuminated  Snellen 
chart  with  the  trial  frame  adjusted  so  as  to  be 
comfortable  and  with  the  centers  of  the  lens  cells 
before  the  pupils  of  his  eyes. 

2nd.  The  left  eye  being  covered  witli  the 
blank  disc  Figure  .51,  note  and  record  the  acuity 
of  vision  of  the  right  eye. 

3rd.  Xow  insert  in  the  trial  frame  a  +..50  D. 
sphere.  If  improvement  occur,  or  if  there  be  no 
impairment,  gradually  increase  the  plus  until 
the  addition  of  a  +.25  sphere  causes  an  impair- 
ment of  the  best  vision  thus  far  secured. 

4th.  Having  secured  all  the  improvement 
possible-  with  plus  spheres,  or,  if  they  liave  been 
rejected,  and  with  the  sphere  in  position  if  used, 
insert  a  +  .50  D.  cvlinder  with  the  axis  at  various 


OPTICAL    PRINCIPLES  13:^) 

positions;  and,  if  improvement  occurs  at  any 
point  in  the  rotation,  select  the  point  of  greatest 
improvement  as  tlie  proper  position  for  the  axis 
and  increase  the  strength  of  the  cyh'nder  so  long 
as  there  is  improvement.  Put  on  all  tJic  pluH 
sphere  or  cijlinder,  that  the  patient  icill  aeei'pt 
zcithout  blurviug  tlie  smallest  letters  he  ean  read. 

.5th.  If  plus  s])heres  and  cylinders  have  heen 
rejected,  exhihit  a  —  ..50  D.  sphere,  and,  if  im- 
provement occurs,  increase  cautiously  as  long  as 
improvement  occurs  taking  care  not  to  over 
correct,  (a  very  easy  thing  to  do  when  minus 
lenses  are  accepted)  because  with  many  people 
greater  acuity  of  vision  is  secured  when  the 
accommodation   is   brought   slightly    into   play. 

6th.  If  minus  spheres  have  not  produced  a 
visual  acuity  equal  to  that  obtained  with  the  pin 
hole,  exhibit  a  —  ..50  D.  cylinder  with  its  axis  at 
various  positions;  and,  if  improvement  occurs  at 
any  position,  select  the  ])oint  of  greatest  improve- 
ment as  the  proper  position  for  the  axis  and 
increase  the  strength  of  the  cylinder  cautiously 
as  long  as  im])rovement  occurs  taking  care  not 
to  over  correct. 

USE  AS  LITTLE  MLXrS  SPIIENL  OH 
(YLIXimU  AS  POSSIBLE 

7th.  Crossed  Cylinders:  If  an  improvement. 
])ut  not  normal  vision  or  vision  ecjual  to  that 
obtained  with  the  ])in  hole,  has  been  secured  with 
a   plus  cylinder,   try  the  cautious   exliibition   of 


134    OPHTHALMOSCOPY,    RETINOSCOPY    AND    REFRACTION 

minus  cylinders  in  combination  with  the  plus  with 
the  axis  at  right  angles  to  that  of  the  latter. 

8th.  When  normal  vision  has  not  been  se- 
cured with  lenses  insert  the  pin  hole  disc  ( Figure 
52)  and  note  if  there  be  furtlier  improvement, 
in  which  event,  it  will  usually  be  possible  to  secure 
an  equal  vision  Avith  lenses. 

9th.  Do  not  hurr}^  or  be  peremptory  with  a 
patient;  while  it  is  inadvisable  to  ask  leading 
questions,  patience  and  tact  while  using  the  trial 
case  will  usually  be  repaid  by  greater  accuracy  of 
results. 

Fogging:  The  so  called  fogging  system  con- 
sists in  placing  a  4-  6.D.  in  front  of  the  eye 
under  examination,  producing  a  strong  artificial 
myopia     with     a     great     reduction     of     vision. 

A  —  l.D.  is  placed  in  front  of  the  +  6.D., 
then  a  —  2.D.  and  so  on  down  until  the  best 
vision  is  produced  by  the  minus  glass.  If  a  ision 
is  then  abnormal,  a  minus  cylinder  is  placed  in 
front  of  the  minus  sphere  turning  the  cylinder 
in  the  trial  frame  until  the  clearest  axis  is  found, 
and  adding  cylinders  at  this  axis  until  the  best 
vision  is  obtained.  The  minus  glass  is  not  re- 
moved from  the  +  6.D.  until  the  next  stronger 
minus  glass  is  in  place. 

The  fogging  method,  building  down  from  a 
+  6.D.  gives  the  same  prescription  or  result  to 
the  author  as  building  up  with  weak  +  glasses 
described  on  page  132. 

The  following  illustrations  from  Dr.  Carl 
Wagner  of  Chicago,  gives  a  good  description  of 
the  fogging  system.     (Pages  188-153.) 


OPTICAL    PRINCIPLES 


135 


Fig.    A. 


Fig.    B. 


Emmetropia 


Myopia 


Hyperopia 


Myopic    Astigmatism 


Hyperopic       Astigmi- 
tism 


Compound    Myopic 
Astigmatism 


Compound    Hyperopic 
Astigmatism 


Mixed   Astigmatisi 


Posterior 


Anterior 


Posterior 


Retina 


136    OPHTHALMOSCOPY,    RETINOSCOPY    AND    REFRACTION 


Fig.  A  (62)  shows  the  foci  of  the  various  errors 
of  refraction,  and  their  relative  position  to  the 
Retina. 

Fig.  B  ( 62 )  sliows  the  position  of  the  foci  after 
a  +  6.D.  spli.  lias  been  placed  in  front  of  eacli 
error. 

Figures    68    and    ()4 
show    Hyperopic    and 
^Myopic     Astigmatism. 
Assuming  the   amount 
of    error    in    both    in- 
stances to  be  2.D.,  and 
the  best  obtainable  vi- 
sion   to    be    20  40,    we 
may,     in     each     case, 
through    the   use   of   a 
+   6  D.   sphere,  bring 
the  focus  far  in  front 
of  the   fundus,   the  resulting  vision  then   being 
much   below    20/40.      In    order   to   regain    this 
20/40  in  Figure  63,  it  is  necessary  to  reduce  the 
-\-   6  D.  sphere,  by  the  gradual  application  of 
weaker  lenses,   and  it  will  invariably  be  found 
that  this  is  finally  accomplished  through  the  use 
of  a  -)-  2  D.  sphere,  when  both  foci  will  be  in 
position  as  in  Figure  64. 

In  order  to  obtain  20/40  in  Figure  64,  we  fur- 
ther reduce  the  strength  of  the  lenses,  until  0  is 
reached,  at  which  time  with  no  lens  in  the  trial 
frame,  the  foci  would  again  be  in  the  same  rela- 
tive position  as  the}^  were. 


Fiff.    63 


OPTICAL    PRINCIPLKS 


137 


In    correcting    tlie    astigmatism,    an    attempt 
must  be  made,  through  the  use  of  spherical  lenses, 
to   obtain   as   good   or    better   vision    tlian    that 
which  exists  in  tlie  un- 
aided eye. 

When  the  result  is 
obtained,  it  becomes  the 
key  to  further  ])roced- 
ure.  I^eaving  the  ac- 
com})hshing  lens  in  the 
trial  frame,  minus  cyl- 
inder lenses  are  now 
used  to  complete  the 
astigmatic  correction. 


Fipr.  64. 


138    OPHTHALMOSCOPY,    RETINOSCOPY    AND    REFRACTION 


Experimental   Correction   of   a   Normal    Eye.      (EMMETROPIA. ) 


Fig.    65 


+  400 


Fig.   61 


Fig. 


+3.50 


Fig.    69. 


Fig.    70. 


OPTICAL    PRI.NCIPLKS 


139 


Experimental    Collection   of  a    Normal    FZye.       (  Emmetropia. ) 
+  2.50  ^ \  -1-2°'^  ~ 


Fig.    71 


+  ).50 


Fig.    73 


Fi!?.    74 


+.50 


PLANO 


Fig.    ?■ 


Fig.    76 


140    OPHTHALMOSCOPY,    RETINOSCOPY    AND    REFRACTION 

The    Correction    of    Hypermetropia. 


Fig.    78. 


-f-  6. 


■1-5.50 


Fig.   79. 


Fig.    80. 


+  5. 


Fig.    81. 


-f  4.50 


Fig.   82. 


OPTICAL    PRINCIPLES 


141 


Tho    Coviecticn    of    Hypeimetio)) 

+  4.00  4  3^50 


Fig.   83 


Fijf.    81 


+  3.00 


+  2.75 


Fit'.    So 


Fi.'.    ^tj 


+2J50 


Fit'.   87 


Fig.    88 


142    OPHTHALMOSCOPY,    RETINOSCOPY    AND    REFRACTION 

The    Correction    of    Myopia. 


Fig.    89. 


Fig.    90. 


Fig.    91. 


PLANO 


Fig.    93. 


Fig.    94. 


OPTICAL    PRINCIPLES 


143 


Fig.    95 


1.^=^ 


Fig 


Fig.    98 


-1.75 


Fig.    99 


Fig.  100 


144    OPHTHALMOSCOPY,    RETINOSCOPY    AND    REFRACTION 

The    Correction    of    Simple    Myopic    Astigmatism. 
NO  LENS 


Fig.    102 


Fig.    103. 


Fig.    104. 


+  3. 


Fig.    105. 


Fig.    106. 


OPTICAL    PRINCIPLES 


145 


The   Correction    of   Simple   Myopic    Asli)j:matism. 
"'"    ^  ^ PLANO 


Fig.    101 


Fig.  108 


-1.^X180 


Fig.   IK 


•1-50^X180 


-2^X180 


Fig.   Ill 


Fig.  11: 


146    OPHTHALMOSCOPY.    RETLXOSCOPY   AND    REFRACTION 


The   Correction    of   Simple   Hypermetropic    Astigmatism. 
4-6. 


Fig.    ll:i. 


Fig:.    114. 


+  5.        X    3:2 


+  4. 


Fig.    115. 


Fig.    116. 


+3.0    -  1.<^X    180 


Fig.    117. 


Fig.    lis. 


OPTICAL    PRINCIPLES 


147 


The  Correction    of   Simple   Hypermetropic    Astigmatisrr 
-f-3.C-J50^X    180  +3.0— I'XISO 


Fig.   119 


Fig.  120 


+  3C— 1.50'X180  ^■3.o  — Z.75  ^X   ISO 


Fiyr.   1 


-f-3.o-3"X  180 


4-3. ^X   90 


Fig.   123 


Fig.   124 


148    OPHTHALMOSCOPY.    RETINOSCOPY    AND    REFRACTION 


The    Correction    of   Compound    Myopic    Astigmatism. 

^  6 


Fig.    125. 


Fig.    125. 


Fig.    127, 


Fig.    I: 


tl. 


NO  LEN5 


Fig.    129. 


Fig.    130. 


OPTICAL    PRINCIPLES 


149 


FiK.    131 


FiK.   1^2 


KKDKE   TO  — 1. 


Ib'O 


Fig.    133 


•1C-50^X180 


Fig.    134 


-1.- -75^X180 


Fig.   135 


-l.c-l'X  ISO 


Fig.    13t; 


150    OPHTHALMOSCOPY.    RETLXOSCOPY    AND    REFRACTION 


The   Correction    of    Compound    Hypermetropic   Astigmatism. 


Fig.    137. 


Fig.    138. 


Fig.    139. 


Fig.    140. 


+  3. 


+  1.50 


Fig.    141. 


Fig.    142. 


OPTICAL    PRINCIPLES 


151 


The    Correction    of    Compound    Hy;.<imetro))ic    A 

+2.25      ^ -.^^^  +2, 


Fig.   143 


Fig.   144 


+2..c-50'XI8a 


Fig.   145 


Fig.    146 


+  2P-1?X180 


Fig.  141 


+  1.3+1?X90 


Fig.  148 


152    OPHTHALMOSCOPY,    RETINOSCOPY    AND    REFRACTION 

The    Correction    of    Mixed    Astigmatism. 


Fig.    149. 


Fig.    150 


+  5. 


Fig.    151. 


Fig.    15i 


Fig.    153. 


Fig.    154. 


OPTICAL    PRINCIPLES 


153 


The    Correction    of   Mixed   AstiKmatism. 
41. C  -rX  180 


FiiT.    15: 


Fitc.   15G 


+  I.=  -I50'X  180 


Fig.   15' 


+  1.  c  -2.'X180 


Fig.   158 


-HI.O-250'X  ISO 


+  1.0-3.^X180 


Fig.    15ii 


154    OPHTHALMOSCOPY,    RETINOSCOPY   AND    REFRACTION 


Ingenious  instruments  have  been  devised  to 
supplant  the  trial  case  for  determining  errors  of 
refraction  and  are  made  without  plus  cylinders 
because  they  are  unnecessary  and  superior  claims 
are  made  both  as  to  speed  and  accuracy  by  their 
makers.  The  instruments  are  constructed  ac- 
curately and  a  descriptive  pamphlet  accompanies 
them. 


Fig.    162      Dynamic    Refractor.       (Hardy.) 


OPTICAL   PRINCIPLES 


155 


Fig.    163.     Ski-Optometer.      (Woolf.) 


156    OPHTHALMOSCOPY,    RETINOSCOPY    AND    REFRACTION 


Fig.  164.     Phoiometer  Trial  Frame.      (Meyrowitz.) 


OPTICAL    PRINCIPLES 


157 


)K.     16")       Phoro-Optometer.       ( Meycrowilz.  I 


158    OPHTHALMOSCOPY,    RETINOSCOPY   AND    REFRACTION 

Cyclopegia:  The  above  rules  apply  when 
determining  the  manifest  error  as  well  as  when 
examining  for  the  static  which  must  be  preceded 
by  putting  the  ciliary  muscle  at  rest  by  the  use 
of  a  cyclopegic. 

HoMATROPiN :  For  transitory  and  incomplete 
cyclopegia  we  may  use  homatropin  freshly  pre- 
pared in  2%  aqueous  solution  or  in  gelatin  discs 
in  the  office  for  an  hour  immediately  preceding 
refraction,  making  three  instillations  of  the  solu- 
tion or  applications  of  the  discs  at  twenty  minute 
intervals,  and  keeping  the  eyes  bandaged  during 
the  intervening  ])eriods.  Twenty  minutes  after 
the  last  instillation,  tlie  full  effect  of  tlie  drug  will 
have  been  produced  and  the  ])atient  is  ready  for 
refraction.  In  adults,  the  cyclo])egia  thus  pro- 
duced is  usually  sufficient  for  this  i^urpose. 

Atropin:  For  a  more  com])lete  and  longer 
lasting  cyclopegia,  we  usually  make  use  of  atro- 
pin  sulphate  in  freshly  prepared  1%  aqueous  so- 
lution for  adults  and  1/^%  solution  for  children. 
The  patient  or  nurse  is  given  the  solution,  labeled 
poison,  witli  instructions  to  instil  one  drop  in 
each  eye  thrice  daily  for  three  days  just  prior  to 
the  refraction  applying  pressure  to  the  lachrymal 
sacs  for  a  moment  after  the  instillation  to  prevent 
absorption  from  the  nose  and  throat.  Some  oper- 
ators use  other  cyclopegic  alkaloids,  but  for  most 
purposes,  one  or  the  other  of  the  above  will  be 
found  satisfactory. 


OPTICAL    PRINCIPLES  159 

Suggestion   yom  the   Use  of  Cwlopegics: 

Great  care  and  adjiistnieiit  is  reciuired  in  the  use 
of  cyclopegies,  and  ^\'hile  no  positive  rules  can  be 
laid  down  and  each  case  must  he  considered  on 
its  own  merits,  the  following-  suggestions  as  to 
their  use  will  be  found  helpful: 

1.  All  children  under  ten  years  of  age  should 
be  refracted  under  cyclopegic.  All  cases  of  as- 
tigmatism should  be  corrected  in  full  but  some 
of  the  sphere  should  be  deducted. 

2.  All  cases  of  strabismus  should  be  refracted 
likewise,  and  as  full  correction  as  will  be  tolerated 
prescribed. 

3.  Asthenopic  patients  who  have  not  found 
relief  with  their  manifest  correction,  should  be 
similarly  treated.  All  of  the  cjdinder,  and  all 
of  the  manifest  spherical,  and  part  of  the  latent 
spherical  is  prescribed  for  constant  wear. 

4.  If  the  manifest  correction  ])roduces  a])- 
proximately  normal  vision  in  an  asthenopic  pa- 
tient with  subnormal  vision,  a  cyclopegic  will 
usually  not  be  required. 

.5.  Before  using  atropin  in  middle  aged  i)a- 
tients,  carefully  consider  the  possibility  of  pro- 
ducing glaucoma  in  that  particular  case. 

().  Cyclopegies  are  rarely,  if  ever,  required  in 
patients  over  forty  years  of  age  and  never  in 
those  over  fifty. 


160    OPHTHALMOSCOPY,    RETINOSCOPY    AND    REFRACTION 


CHAPTER     IX 

APPLIED    REFRACTION 

With  these  general  considerations  understood, 
we  are  ready  to  take  up  their  apphcation  in  the 
diagnosis  and  treatment  of  the  refractive  errors 
of  the  eyes,  which,  in  this  connection  must  be 
considered  as  most  highly  developed  camerae 
obscurae  functioning  at  once  independently  and 
in  perfect  unison.  Considered  optically,  the 
normal  eye  may  well  be  described  as  the  ideal 
camera;  having  an  iris  diaphragm  that  acts  au- 
tomatically to  meet  the  requirements  of  both 
illumination  and  focus  as  determined  by  the  dis- 
tance from  the  photographed  object,  a  perma- 
nent sensitive  plate  and  a  method  of  focusing  not 
by  changing  the  length  of  the  dark  chamber; 
but  by  varying  the  dioptric  strength  of  the  re- 
fractive system  from  the  static  43.5-D  deter- 
mined by  dividing  100  centimeters  by  23  milli- 
meters, the  length  of  the  eye,  required  to  focus 
images  of  objects  beyond  twenty  feet  to  much 
more,  making  possible  the  focussing  of  the  diver- 
gent rays  given  off  by  sources  of  illumination 
nearer  than  20  feet.     (Fig.  166.) 

Accommodation:  The  function  of  thus  in- 
creasing the  dioptric  strength  of  the  lens  system 


APPLIED    REFRACTION  161 


¥\n.   16tj.     Section  of  the  Anterior  Portion  of  the  Eyeball.     The  dotted  lines 
illustrate  the  changes   during   accommodation.      (May.) 

of  the  eye  is  called  accommodation.  The 
mechanism  of  its  production  is  illustrated  in  Fig- 
ure 166  showing  how  the  action  of  the  circular 
fibres  of  the  ciliar}^  muscle  relaxes  the  suspensory 
ligament  of  the  crystalline  lens  according  to  the 
theory  of  Helmholtz,  the  one  usually  accepted, 
which  by  its  own  elasticity  increases  its  convex- 
ity; or  according  to  the  theory  later  advanced 
by  Tscherning,  who  claims  that  in  contraction 
the  ciliary  muscle  compresses  the  suspensory  liga- 
ment decreasing  its  circumference,  tlius  simi- 
larly affecting  the  lens  and  forcing  it  to  bulge  in 
its  antero-posterior  diameter.  However  pro- 
duced, the  change  in  curvature  takes  place  prin- 
cipally in  the  anterior  surface,  ])ossibly  because 
of  the  reduced  resistance  offered  by  the  fluid 
aqueous  as  com])ared  with  that  offered  by  the 
dense  vitreous. 

A:\rpiJTUDK  OF  Accom:modatiox:  Witli  the 
accommodation  in  abeyance,  the  crystalline  lens 
exerts  about  10  I),  of  the  total  (more  tlian  40) 
possessed  by  the  normal  eye.  But.  as  has  been 
worked  out  by  Donders,  this  amount  is  appre- 


162    OPHTHALMOSCOPY,    RETINOSCOPY    AND    REFRACTION 

ciably  increased  with  the  accommodation  in 
force;  the  amount  of  increase,  because  of  the 
gradual  loss  of  lens  elasticity  with  increasing 
years,  varying  inversely  with  the  patient's  age. 
The  amount  of  possible  increase  of  the  accom- 
modative function  is  called  the  amplitude  of 
accommodation  and  is  of  very  great  importance 
in  the  consideration  of  hypermetropia  and  pres- 
byopia, both  of  which  will  be  discussed  later.  The 
results  of  Donder's  work  is  set  forth  in  the  fol- 
lowing table: 

Amplitude  of  Accommodation 
Age  Age 


10 

14.00  D. 

45 

3.50  D 

15 

12.00  D. 

50 

2.40  D 

20 

10.00  D. 

55 

1.75  D 

25 

8.50  D. 

60 

1.00  D 

30 

7.00  D. 

65 

.75  D 

35 

5.50  D. 

70 

.25  D 

With  the  optical  principles  of  the  previous 
chapter  and  the  above  dioptrics  of  the  human 
eye  well  in  mind,  we  will  now  take  up  the  dis- 
cussion of  the  diagnosis  and  treatment  of  re- 
fractive errors.  Since  it  is  the  aim  of  this,  as  of 
all  the  chapters,  to  give  the  student  a  working, 
as  well  as  an  academic  knowledge  of  the  sub- 
jects discussed;  and  since  all  our  cases  come  to 
us  as  unknown  Avith  tlie  diagnosis  to  be  worked 
out,  we  will  endeavor  to  accomplish  our  aim  by 
means  of  drawings. 


APPLIED    REFRACTION  163 

Case  I.  J.  S. — Bookkeeper,  age  26,  com- 
plains of  irregular  intermittent  frontal  head- 
aches. 

After  preliminary  ocular  inspection  with  ever- 
sion  and  careful  examination  of  the  lids  and 
palpation  of  the  lacrymal  sacs  with  negative 
results,  he  is  comfortahly  seated  at  a  distance 
of  20  feet  from  the  well  illumined  Snellen  cliart, 
the  trial  frame  properly  adjusted,  the  left  eye 
covered  with  the  blank  disc,  and  he  is  asked  to 
read,  when  it  is  found  that  he  can  readily  dis- 
tinguish the  letters  in  the  line  that  should  be  read 
at  20  feet.  A  +  .50  D.  sphere  is  placed  in  the 
trial  frame  in  front  of  his  eye  whicli  blurs  his 
vision  perceptibly.  The  sphere  is  removed  and 
a  +  .50  D.  cylinder  is  placed  before  the  eye 
with  its  axis  at  90^  and  is  immediately  rejected 
as  it  is  Avhen  turned  to  all  other  meridians.  The 
patient  is  not  hurried,  the  lenses  are  changed 
deftly  and  the  questioning  done  tactfully  and 
deliberately.  While  it  is  very  unlikely  tliat  the 
eye  can  be  myopic  with  normal  vision,  a  minus 
.50  sphere  is  now  inserted  and  the  patient  reports 
on  questioning  tliat  the  lens  seems  to  put  a  strain 
on  the  eye  althougli  lie  can  see  as  well  or  perhaps 
a  little  better  with  it  than  without.  Accordingly, 
the  sphere  is  removed  and  a  —  .50  D.  cylinder 
inserted  with  its  axis  at  180  with  a  similar  result 
which  continues  when  its  axis  is  slowly  rotated 
tlirough  an  arc  of  90"'.  The  lens  is  removed  and 
the  blank  disc  taken  from  the  left  eye  and  placed 
over  the  right  and  the  former  refracted  as  was 
the  right  and  with  a  similar  result. 


164    OPHTHALMOSCOPY,    RETINOSCOPY    AND    REFRACTION 

It  is  decided  that  the  ])atieiit  has  no  manifest 
eiTor.  In  order  to  be  absohitely  certain,  the 
patient  was  asked  to  return  next  day  for  exami- 
nation under  a  cyclopegic,  wlien  after  the  use  ol' 
homatropin  as  previously  described  and  after  a 
repetition  of  the  above  ])rocedures,  the  same  re- 
sults were  verified  bv  retinoscopy.  (See  Chap- 
ter XI.) 

We  are  therefore  forced  to  tlie  conclusion  tliat 
the  refractive  condition  of  his  eyes  is  normal  and 
that  the  cause  of  the  headaches  must  be  sought 
for  in  some  other  condition  of  the  eyes  or  even 
in  some  other  structure,  if  during  the  remainder 
of  the  complete  systematic  ocular  examination, 
no  condition  is  found  warranting  the  symptoms 
complained  of. 


Fig.    167.      The   Emmetropic    Eye   in         Fi-.     168.       The     Emmetropic     Eye 
a   State  of  Rest.      (May.)  During   Accommodation.       (May.) 

Emmetropia:  Emmetropia  (Figure  167)  is 
that  condition  in  which  with  the  accommodation 
in  abeyance,  the  relation  of  dioptric  strength  to 
the  antero-posterior  diameter  of  the  eye  is  such 
that  all  rays  of  light  originating  beyond  20  feet 
from  the  eye  are  brought  to  a  focus  on  the  retina. 
In  other  Avords,  the  eye  may  be  said  to  be  at  rest 
when  looking  at  a  distance  thus  saving  all  of 


APPLIED    REFRACTION  165 

the  accoiiiinodative  force  for  near  work  as  sho^vn 
in  Figure  168. 

As  mentioned  above,  jjeople  with  normal  eyes 
frequently  come  to  us  seeking  relief  from  symp- 
toms wliich  they  erroneously  attribute  to  eye 
conditions  and  we  must  be  able  to  diagnose  em- 
metropia  as  accurately  as  we  do  ametropia.  In- 
deed we  must  know  the  normal  if  we  are  to 
recogni'/c  a  deviation  from  it.  In  the  above  case 
the  wearing  of  any  lenses  other  than  absolutely 
neutral  ones  would  be  imdesirable. 

In  an  eai'lier  chapter,  we  emphasized  the 
importance  of  making  ocular  examinations  sys- 
tematically. The  author  wishes  to  reiterate  that 
statement  here,  to  emphasize  the  importance  in 
the  use  of  the  trial  case,  and  to  describe  and 
illustrate  a  system  for  its  use  which  being  faith- 
fully followed  will  give  the  nearest  possible  ac- 
curacy of  results. 

Case  II.  ^liss  A.  C — Stenographer,  Aged  22. 
Complains  that  eyes  tire  quickly  at  her  work  and 
that  severe  occipital  headaches  come  on  during 
the  afternoon.  She  is  wearing  -[-  0.7.5  D.  each 
eye. 

Following  the  rules  for  refraction,  pages  132- 
103,  we  arrive  at  the  following  result: 

K.  E.  20/1.5  +  1.25  =  20  15. 

L.  E.  20/15  +  1.50  =  20/15. 

The  diagnosis  of  the  above  and  of  the  follow- 
ing four  cases  of  liypermetropia  with  its  correc- 
tion by  lenses  is  shown  in  the  following  figures. 


166    OPHTHALMOSCOPY,    RETINOSCOPY   AND    REFRACTION 


Hypermetropia:  In  liypermetropia,  there  is 
a  disturbance  in  the  relation  between  dioptric 
power  and  length  of  eye  as  a  result  of  which,  with 
the  accommodation  in  abeyance,  parallel  rays  of 
light  reach  the  retina  having  come  to  a  focus  as 
is  shown  in  Figure  169. 

While  the  condition  is 
usually  thought  of  as  the 
result  of  shortening  of  the 
antero-posterior  diameter 
as  shown  in  Figure  170,  it 
may  be  caused  by  a  defic- 
iency of  the  static  refrac- 
tion of  the  eye  by  exertion 
of  the  accommodative 
function. 

If  the  deficiency  is 
within  amplitude  of  ac- 
commodation, the  patient 
may  be  able  to  maintain 
clear  distant  vision  more 
or  less  constantly,  with 
usually  a  more  or  less 
complete  failure  of  the 
function  for  near  work 
and  some  or  all  of  the  symptoms  of  eye  strain. 
How  this  same  end  may  be  served  by  a  convex 
lens,  giving  constant  clear,  easy,  distant  vision 
and  conservation  of  the  accommodative  function 
for  its  normal  use  in  near  vision  is  shown  in  Fig- 
ure 171. 

Case  III.  R.  R.,  Aged  35.  Laborer.  Com- 
plains of  recent  failure  of  distant  vision.     States 


Hypermetropic 

State     of     Rest. 

(May.) 

Fig.       170.         Hypermetropic 

Eye   During-    Accomm.odation. 

(May.) 

Fig.       171.         Hypennetropia 

Corrected  by  a  Convex  Lens. 

(May.) 


APPLIED    REFRACTION  167 

that  he  never  was  able  to  read  for  any  length  of 
time.  The  rules  on  ])age  132  were  followed  with 
result  as  follows : 

K.  E.  20/50  +  4.50  sph.  =  20/20 

L.  E.  20/60  +  5.00  sph.  =  20/20. 

Given  above  for  eonstant  wear. 

Case  IV.  INlaster  G.  L.,  Aged  5.  ]Mother 
states  that  left  eye  has  tin-ned  in  for  last  three 
or  more  years.  The  manifest  was  taken  aeeord- 
ing  to  the  rules,  page  1.-32  using  the  illiterate 
chart. 

11.  E.  20/40  +  2.50  =  20/20 

L.  E.  20/80  +  4.00  =  20/50 

The  mother  was  given  a  ^4%  aqueous  solution 
of  atropin  sulphate  with  instructions  to  instil 
two  drops  in  each  eye  morning,  noon,  and  night, 
and  requested  to  bring  the  child  in  three  days 
^vhen  the  following  results  verified  by  the  use  of 
the  retinoscope  were  obtained. 

II.  E.  20/100  +  4.00  =  20/20 

L.  E.  20/200  +  5.50  =  20/50 

Given  right  eye  +  3.50  sph.  —  left  eye  +  5.00 
sph.  with  instructions  to  use  one  drop  of  1^% 
solution  of  atropin  sul])hate  in  each  eye  before 
retiring  every  third  day  and  to  report  at  the  end 
of  one  month  for  examination. 

Case  V.  Miss  M.  H.,  Age  25.  Teacher. 
Complains  that  glasses  she  is  now  wearing  which 
w^ere  fitted  two  months  ago  have  failed  to  relieve 
frontal  headache  and  epi])hora  complained  of  at 
that  time. 

R.  E.  20/20  +  .50  =  20/20 

L.  E.  20/20  +  .50  -=  20/20 


168    OPHTHALMOSCOPY,    RETINOSCOPY    AND    REFRACTION 

Examination  of  her  glasses  show  them  to  be 
the  same.  Three  instillations  of  a  2%  solution 
of  homa tropin  hydrobromate  Avere  made  at 
twenty  minute  intervals  and  the  refraction  re- 
jjeated  twenty  minutes  after  the  last  instillation 
with  the  following  results: 

R.  E.  20A0  +  1.75  sph.  =  20/20 

L.  E.  20/40  +  1.75  sph.  =  20/20 

Given  plus  1.00  sph.  both  eyes  with  instruc- 
tions to  use  them  constantly  and  to  report  the 
result  in  a  week. 

Case  VI.  N.  A.,  Aged  23.  Electrician. 
States  that  while  taking  a  civil  service  examina- 
tion recently  it  was  discovered  that  he  did  not 
have  useful  vision  in  his  left  eye.  Following  the 
rules  page  132  in  order  we  find  the  following: 

R.  E.  20/20    +     .50  =  20/15 

L.  E.  20/200  +  4.50  =  20/30 

In  practice  it  is  found  that  a  difference  of  more 
than  about  four  dioptres  will  not  be  accepted  be- 
cause the  difference  in  size  of  the  retinal  images 
makes  binocular  vision  impossible.  Since  he 
complains  of  no  discomfort  nor  other  symptoms 
he  was  advised  not  to  wear  glasses. 

Case  VII.  Miss  J.  C,  Aged  40.  Bookkeeper. 
Comes  wearing  glasses  which  she  states  she  had 
been  advised  to  wear  to  save  her  eyes  and  which 
have  always  been  uncomfortable  although  ac- 
cording to  the  rules  we  find  first  that  the  visual 
acuity  is  20/30  in  the  right  eye  and  that  neither 
convex  spheres  nor  cylinders  improve  it.  Con- 
cave spheres  are  found  to  help  a  —  .75  D.  sphere 
giving  a  visual  acuity  of  20/20  which  is  not  im- 


\PPLIKI)    HKFRACTION 


160 


proved  by  a  concaxc  cylinder.  A  similar  result 
was  obtained  with  the  left  eve  so  we  have: 

R.  E.  20/30  —  .7,5  sph.  =  20/20 

L.  E.  20/30  —  .75  sph.  =  20/20 

She  was  asked  to  return  for  examination  under 
cyclopegia  which  done  the  next  day  <j'a\  e  the  fol- 
lowing : 

11.  E.  20/40  —  ..50  =  20/20 

L.  E.  20/40  —  .50  =  20/20 

She  was  advised  not  to  Avear  glasses  as  in  her 
refractive  condition  there  was  no  inconvenience 
other  than  a  slight  impairment  of  distant  vision, 
so  shght  as  to  be  disregarded.     In  this  as  in  the 


Fig.    IT: 


Myopic    Eye.       (Thoring- 
ton.l 


Fig.   173.      Myopic  Eye  Corrected  by 
Concave  Lens.      (Thorington.  i 


following-  two  cases  the  refractive  error  is  called 
^lyopia.  This  is  described  as  a  disturbance  of 
the  relation  between  dioptric  power  and  length 
of  eye;  and  is  the  o])posite  of  that  in  hy])ermetro- 
pia,  that  is,  with  the  eye  at  rest,  parallel  rays  are 
focussed  within  the  eye  and  crossing  ])roduces  a 
circle  of  diffusion  on  the  retina  with  resultant 
poor  distant  vision  as  shown  in  figure  172. 

While  the  condition  may  he  due  to  excessive 
static  refraction,  it  is  usually  caused  by  actual 
increase  of  the  antero-posterior  diameter  of  the 


170    OPHTHALMOSCOPY,    RETLNOSCOPY    AND    REFRACTION 

eye.  Figure  173  shows  the  same  eye  with  the 
proper  concave  lens  before  it  which  causes  the 
parallel  rays  to  diverge  just  enough  to  have  them 
focus  on  the  retina  after  having  passed  through 
the  eye's  dioptric  system  with  the  accommodation 
at  rest 

Case  VIII.  H.  H.  Aged  12— Student. 
Referred  by  teacher  who  has  observed  that  dis- 
tant vision  is  subnormal  as  evidenced  by  inability 
to  see  work  on  blackboard  from  rear  of  room. 
Applying  rules  page  132  one  to  five  in  order,  we 
have : 

R.  E.  20/80  —  2.50  sph.  =  20/25 
L.  PI  20/100  —  3.00  sph.  =  20/25 
Which  correction  when  tried  for  a  few  mo- 
ments in  the  office  was  found  to  tire  the  eyes  for 
near  work  and  the  following  correction,  with 
which  near  work  would  be  comfortably  done,  was 
given  for  constant  wear. 

R.  E.  —  1.50  sph.  =  20/40 
L.  E.  —  2.00  sph.  =  20/40 
The  strongest  glass  a  myopic  patient  can  read 
with  comfort,  will  usually  be  worn  with  satisfac- 
tion. 

Case  IX.     Miss  J.  B.  Aged  30 — Seamstress. 
Complains  of  inability  to  see  at  distance  with- 
out strong  minus  glasses. 

R.  E.  20/200  —  6.00  sph.  =  20/40 
L.  E.  20/100  —  5.00  sph.  =  20/30 
This  correction  gave  satisfactory  distant  vision 
but  could  not  be  used  for  near  work. 

R.  E.  —  3.00  sph.  distant  vision  20/60 
L.  E.  —  2.00  sph.  distant  vision  20/50 


ASTIGMATISM 


171 


Since  this  gave  too  poor  distant  vision  to  be 
of  use,  she  was  given  two  pair  of  glasses  which 
proved  quite  satisfactory.  Full  correction  for 
distant  and  for  work  R.  —  8.00  sph.  L.  —  2.00 
sph. 

Causes  of  Astigmatism:  An  equal  refrac- 
tion in  different  meridians  of  the  same  eye  may  be 
due  either  to  an  irregularity  of  the  cornea  or  of 
the  lens,  but  practically  is  the  result  of  combined 
conditions  in  both  of  them  as  is  shown  by  tlie  fact 
that  often  eyes  having  a  moderate  corneal  astig- 


Fiqr     175       Corneal    Reflection    of    Placedo' 
Disc    in    Emmetropia. 


Fig.    176.      Corneal    Reflection    of    Placedo"s 
Disc    in    Regular    Astigmatism. 


Fig.    174.      Keratoscope 


Fig.    177.      Corneal    Reflection    of    Placedo's 
Disc     in     Irregular     Astigmatism.       (May.  t 


matism  are  free  from  tlie  condition  when  the  en- 
tire dioptric  apparatus  is  considered — the  corneal 
astigmatism  is  corrected  by  a  lenticular  one. 

Means  of  Diagnosis  of  Astigmatism:  In 
addition  to  the  subjective  methods  to  be  described 
for  determining  and  measuring  the  amount  of  the 


172    OPHTHALMOSCOPY,    RETINOSCOPY    AND    REFRACTION 


have   certain   objective   ones    for 
One  of  the  earhest  devised  in- 
use  in  this  connection  is  Placedo's 
(Figure  174.) 

a  disc  on  the  face  of  Avhich  are 
painted  alternating  concentric  black  and  white 
circles  to  which  is  attached  a  handle  for  conve- 
nience in  handling.  AVIien  this  disc  is  held  before 


condition,    we 
diagnosing  it. 
striiments  for 
keratoscope. 
Consists  of 


P'ig     178.     Ophthalmometer 


Hardy.) 


ASTIGMATISM  173 

an  eye  its  reflection  assumes  one  ol'  the  t'oi-nis 
illustrated.     (Figs.  175,  176  and  177.) 

Another  instrument  for  investigating  the  cor- 
neal curvatures  is  the  ophthalmometer,  Figure 
178,  directions  for  the  use  of*  which  accom])any 
the  instrument. 

The  student  will  note  that  hoth  ol*  tlie  ahove 
instruments  investigate  the  condition  of  the  cor- 
nea only,  and  he  will  hear  in  mind  that  the  cor- 
neal error  may  be  corrected  by  the  proper  defect 
in  the  lens.  There  is  one  means,  however,  of 
gaining  information  concerning  the  total  condi- 
tion resulting  from  l)oth  corneal  and  lenticular 
irregularity,  and  that  is  by  the  application  of 
direct  oplit]iahiiosc()])y.  If,  on  looking  at  the 
disc,  it  is  observed  to  i)e  distinctly  oval,  there  is 
a  very  great  likelihood  of  the  eye  being  astig- 
matic; and,  if  the  refraction  of  the  eye  by  means 
of  this  instrument,  as  shown  by  refracting  the 
vessels  running  at  right  angles  to  each  other,  is 
different  in  different  meridians,  the  condition  is 
positively  diagnosed. 

FoK.Ms  OF  As'riG:MATis:M :  Astigmatism  or 
curvatin-e  ametro])ia  is  described  as  regular  when 
there  is  no  break  in  tlie  continuity  of  any  of  the 
refracting  surfaces,  and  the  difference  in  tlieir 
curvature  proceeds  regularly  from  that  of  mini- 
mum radius  to  that  of  tlie  minimum  one  when  the 
keratascope  produces  an  image  similar  to  the  one 
illustrated  in  Figure  176. 

Wlien  there  is  a  l)reak  in  the  surface  of  any  of 
the  refracting  mediae  or  their  eui-vatures  do  not 
proceed  regularly  as  described  above,  an  irregu- 


174    OPHTHALMOSCOPY,    RETINOSCOPY    AND    REFRACTION 

lar  astigmatism  is  produced  which  is  not  correct- 
ible  with  lenses.  Practically  this  can  occur  with 
the  cornea  only  as  the  result  of  injur}^  or  disease 
and  the  keratascope  image  will  resemble  that 
shown  in  Figure  177. 

The  condition  is  further  described  as  "with  the 
ride"  when  the  eye's  greatest  dioptric  power  lies 
in  or  near  the  vertical  meridians,  the  usual  con- 
dition, and  which  is  attributed  to  shortening  of 
the  radius  of  cinwature  of  the  cornea  by  lid  pres- 
sure. When  the  greatest  dioptric  power  lies  in 
or  near  the  horizontal  meridian  the  astigmatism 
is  described  as  "against  the  rule." 

Regular  Astigmatism:  These  are  also  con- 
sidered as  forms  of  the  basic  ametropias  and  in 
tliis  connection  are  described  as  compound  Hy- 
peropic  astigmatism  of  whicli  the  last  case  is  an 
example. 

1.  Simple  Hyperopic  Astigmatism  (Page 
181),  in  which  the  eye  is  hypermetropic  in  one 
meridian  and  is  emmetropic  in  the  one  at  right 
angles  to  it. 

2.  Simple  INIyopic  Astigmatism  (Page  181), 
in  whicli  one  meridian  is  emmetropic  and  the 
other  myopic. 

3.  Compound  Hypermetropic  Astigmatism, 
(Page  181)  in  which  both  meridians  are  hyper- 
metropic, but  to  a  different  degree. 

4.  Compound  INIyopic  Astigmatism,  (Page 
181)  in  wliicli  ])oth  nieridians  are  myopic  but  to 
a  different  degree. 

5.  Mixed  Astigmatism    (Page   181),   where 


ASTIGMATISM  175 

one  meridian  is  hypermetropic  and  the  other 
mj^opic. 

All  of  the  ahove  five  forms  may  he  either  with 
or  against  the  rule  and  are  eorreetihle  with 
lenses. 

Symptoms  of  Astigmatism:  If  tlie  astig- 
matic error  be  high  in  amount,  the  only  symptom 
usually  noted  is  a  low  visual  acuity;  })ut,  if  it 
exists  in  only  a  moderate  degree  and  the  patient 
lias  an  active  accommodation,  he  may  suffer  with 
the  most  marked  asthenopic  sym])toms  especially 
if  engaged  in  work  calling  for  accurate  vision 
because  of  the  eye's  efforts  to  ])roduce  it  by  con- 
stant varying  of  the  amount  of  ciliary  muscle 
action  in  use.  Any  or  all  of  the  symptoms  that 
are  complained  of  may  be  described  and  all 
usually  disappear  promptly  with  the  Avearing  of 
the  proper  correcting  lenses. 

Prevalence  and  Importance  of  Astigma- 
Tisvr :  Curvature  ametropia  Avith  its  many  Forms 
is  the  most  common  of  refractive  troubles,  and 
considered  on  the  basis  of  the  discomfort  it 
causes,  it  is  imdoubtedly  the  most  im])()rtant. 
liikewise.  it  is  the  most  difficult  to  estimate  ac- 
curately which  has  resulted  in  the  development 
of  numerous  accessory  devices  and  various  s])ecial 
charts  for  use  in  subjective  refracting.  Of  the 
accessories,  all  may  well  be  discarded  save  the 
stenopic  slit,  which  will  often  be  found  useful  in 
locating  tlie  ])rinci])al  meridians  when  they  have 
not  been  located  by  other  methods. 

Stenopic  Si-rr:  Figure  .5:^  This  aeeessoi-y  is 
used  by  placing  it  in  the  properly  adjusted  trial 


176    OPHTHALMOSCOPY,    RETINOSCOPY    AND    REFRACTION 

frame  and  asking  the  patient  to  look  at  the  Snel- 
len chart,  the  operator  meanwhile  rotating  the 
cell  of  the  trial  frame. 

If  the  patient  sees  hetter  in  one  meridian  than 
in  others,  very  likely  he  is  astigmatic,  and  the 
meridian  at  which  he  sees  best,  which  should  be 
accepted  only  after  several  revolutions  of  the 
disc  preferably  by  the  patient  liimself,  is  one  of 
the  principal  meridians.  In  this  event,  he  will 
have  the  poorest  vision  while  using  the  slit  when 
it  is  rotated  to  ninety  degrees  from  the  first  one 
chosen.  Some  operators  use  the  stenopic  slit 
throughout  the  work  with  the  trial  case  refrac- 
ting each  meridian  separately,  and  combining 
the  results  for  the  prescription,  but  tliis  is  not  to 
be  recommended. 

Astigmatic  Charts  :  Xumerous  special  astig- 
matic charts,  all  modifications  of  the  clock  dial 
chart  (Figure  61),  have  been  devised,  but  they 
are  not  to  be  recommended  since  they  really 
are  little  or  no  improvement  over  the  original 
without  whicli  some  operators  get  along  very 
well  depending  on  visual  results  alone  as  deter- 
mined with  the  Snellen  type. 

Case  X.    C.  J.  Aged  2,5 — Telegrapher. 

Complains  of  frontal  headaches  that  increase 
toward  evening.  On  refracting  systematically 
we  find : 

R.  E.  20/20  -j-  .50  cvl.  ax.  90  =  20/20. 

L.  E.  20/20  +  .37  cyl.  ax.  90  =  20/20. 

Under  homatropin  the  following  was  secured : 

R.  E.  20/60  +  .75  sph.  I  +  .50  cyl.  ax.  90  == 
20/20. 


ASTIGMATISM  177 

J^.  K.  20/  ()()  +  .7.3  spli.  Z  +  ^^7  cvl.  ax.  90  = 
20  20. 

He  was  given : 

K.  E.  +  .2.5  sph.  1  +  ..50  evl.  ax.  90. 

L.  E.  +  .25  sph.  _   +  .37  cyl.  ax.  90. 

Diagnosis:  Coni])oiind  Hypermetropic  Astig- 
matism.    Figure  133. 

Case  XI.  J.  J.   xVged  22^Porter. 

Complains  of  poor  distant  and  near  vision. 
With  tlie  reguhir  ])rocednre  Ave  find  tlie  vision 
R.  E.  to  he  20  80  ])his  s])heres  are  rejected  hut 
plus  cylinders  with  tlie  axis  at  13.5  are  accepted 
readily  as  tliey  are  in  the  left  eye,  save  that  the 
axis  is  at  -15.    The  result  is  as  follows: 

R.  E.  20/80  P.  H.  20/30  +  2.o0  ax.  13.5  = 
20  30. 

E.  E.  20  100  P.  H.  20  40  +  3.00  ax.  4.5  ^ 
20/40. 

Diagnosis:  Simple  Hypermetropic  Astigma- 
tism.   Figure  179. 

Case  XII.   :\Irs.  G.  F.    Age  23- -Housewife. 

Complains  of  poor  vision,  epi])hora  and  head- 
aches.   Applving  the  rules  in  order  we  find: 

R.  E.  20^80  +  1.25  cyl.  ax.  100  =  20/50  C 

—  .75  cvl.  ax.  10  =  20/20. 

L.  E.'  20/65  +  1.00  cyl.  ax.  100  =  20^40  C 

—  .50  cyl.  ax.  10  =  20/20. 
Diagnosis:    ]Mixed  Astigmatism. 

Case  XTTI.   A.  C.  Aged  35— Bookkeeper. 

Complains  of  usual  symptoms  for  near  work 
and  states  that  condition  has  heen  increasing 
since  heginning  to  wear  present  correction  ten 
days   ago.     Examining  systematically,  we   find 


178    OPHTHALMOSCOPY,    RETINOSCOPY    AND    REFRACTION 

that  plus  spheres  and  cyhnders  are  rejected  and 
that  a  — .50  sphere  improves  the  vision.  R.  E. 
from  20/60  to  20/40  and  that  a  —.50  D.  cylinder 
improves  anywhere  near  180  degrees.  Using  the 
stenopic  slit,  we  determine  the  location  of  the 
meridian  as  at  170  degrees  and  apply  one  cyl- 
inder with  axis  at  that  point. 

Completing  the  refraction  of  that  and  the  left 
eye  we  have : 

R.  E.  20/60  P.  H.  20/30  —  .50  sph.  C  —  .75 
cvl.  ax.  170  =  20/20. 

'  L.  E.  20/80  P.  H.  20/30  —  .75  sph.  3  —  1.00 
cyl.  ax.  10  =  20/25. 

Diagnosis:  Compound  myopic  astigmatism. 
Figure  179. 

Examination  of  his  glasses  found  him  to  be 
wearing  the  same  lenses  save  that  the  axes  were 
at  180  degrees.  They  were  given  to  him  with 
the  axis  at  the  proper  position  with  very  satis- 
factory results. 

Aphakia:  There  remains  one  more  anomaly 
of  the  static  refraction  of  the  eye,  a  high  degree 
of  hypermetropia  or  more  often  compound  hyper- 
metropic astigmatism,  produced  artificially  either 
by  complete  dislocation  of  the  crystalline  lens 
within  the  vitreous,  or  more  often  by  its  removal 
because  of  its  being  cataractous.  After  such  dis- 
location or  removal,  the  eye  is  said  to  be  aphakic. 

The  Cokrectiox  of  Aphakia:  In  the  cor- 
rection of  this  condition,  the  same  rules  are 
followed,  but  practice  has  demonstrated  that 
roughly  speaking  a  +  10  D.  sphere  will  be  re- 
quired to  take  the  place  of  the  removed  lens 


ASTIGMATISM  1 79 

with  or  without  a  cyh'nder  to  correct  the  corneal 
deformity  resulting  from  the  incision.  Another 
practical  point  is  that  when  using  the  pin  hole 
disc  to  determine  the  visual  acuity  that  may  be 
expected — that  the  placing  a  -4-  10  D.  sphere 
before  it  in  the  trial  frame  usually  give  better 
results. 

Since  the  cylinder,  if  required  at  all,  is  usu- 
ally of  considerable  strength,  great  care  must  be 
exercised  in  locating  its  axis  correctly.  The  use 
of  the  stenopic  slit  will  prove  of  very  great  assist- 
ance in  doing  this.  Often  the  distortion  of  the 
test  chart  with  a  +  5  D.  sphere  before  the  eye 
will  give  a  valuable  clue  to  the  location  of  the 
axis. 

Since  changes  in  the  dioptric  power  of  the  eye 
continue  for  some  little  time  after  the  operation, 
an  aphakic  patient  should  not  liave  his  correction 
prescribed  until  six  weeks  have  elapsed  after  his 
discharge;  one  other  thing  that  must  be  remem- 
bered is  that  a  monocular  a])hakic  ])atient  can- 
not wear  his  correction  if  he  has  normal  or  nearly 
normal  vision  in  his  other  eye.  However,  he 
should  be  refracted  so  that  you  and  he  may  know 
just  what  vision  he  may  expect  in  the  event  of 
the  other  eye  becoming  incapacitated. 

Case  XIV.  T..  A.  Aged  24,  I^aborer.  Swollen 
opaque  lens  resulting  from  penetrating  injury 
ten  days  previously,  removed  from  right  eye  eight 
weeks  ago  because  of  secondary  glaucoma,  apply- 
ing the  rules  we  have. 


180    OPHTHALMOSCOPY,    RETINOSCOPY    AND    REFRACTION 

R.  E.  20/200  P.  H.  +  10.00  =  20/20  +  6.00 
C  +  2.00  ax.  80  =  20/20. 
L.  E.  20/20  +  .25  =  20/20. 

Glasses  were  not  prescribed  because  they  would 
not  be  practical. 

Case  XV.  J.  C.  Aged  69,  Farmer.  Both 
lenses  removed  six  weeks  ago  because  of  senile 
cataract.    Following  the  rules : 

R.  E.  10/200  P.  H.  20/2.5  +  9.00  =  20/25. 

L.  E.  15/200  +  8.00  -^  1  cvl.  ax.  105  =  20/25 
P.  H.  20/25. 

Given  above  for  distance  with  suitable  correc- 
tion for  reading  as  discussed  under  presbyopia. 

Recapitulation:  This  completes  the  discus- 
sion of  the  static  errors  of  refraction  which  will 
be  closed  by  again  emphasizing  the  need  of  fol- 
lowing the  rules  page  142  or  pages  138-153  in 
the  order  given  and  which  are  epitomized  in  the 
following  combined  figure  and  table. 


In  the  normal  eye  a  +  50  .sph  or  cyl 
would  diminish  tlie  visual  acuity,  so 
would  —  sph  and  —  cyl  lenses.  Any  of 
them  would  remove  the  focal  point 
from  the  retina. 


In  hyperopia,  a  +  50  sph  would  im- 
prove vision,  rays  of  light  being  con- 
verged and  brought  forward  on  the 
retina. 


Ill  coiiiji.  hyjx'ropic  astigmatism,  a  -(- 
sph  lens  will  improve  the  vision  and 
combining  a  +  cyl  lens  with  it  would 
correct  the  defect. 


In  simple  hyperopic  astigmatism,  a  + 
sph  would  not  improve  vision;  a  +  cyl 
lens  would  converge  rays  of  light  in 
one  median,  bringing  it  on  the  retina. 


In  mixed  astigmatism,  +  sph  or  —  sph 
lenses  will  not  improve  the  error.  A  -f- 
cyl  lens  would  improve  it  and  a  —  cyl 
lens  at  right  angles  in  the  former  would 
correct   the    error. 


In  myopic  astigmatism,  a  -|-  sph  would 
not  improve  vision;  a  —  cyl  lens  w4th 
the  sph  would  correct  the  error. 


In  myopia  a  +50  sph  or  +  50  cyl  would 
decrease  the  vision;  a  —  spli  would  di- 
verge the  rays  of  light  and  bring  the 
focus  on  the  retina. 


In  comp.  myopic  astigmatism  a  —  sph 
lens  would  improve  tlie  vision;  a  —  cyl 
lens  with  the  spli  would  correct  the 
error. 

Fip:.  179. 


182    OPHTHALMOSCOPY,    RETINOSCOPY   AND    REFRACTION 

Presbyopia  :  In  an  earlier  section,  the  func- 
tion of  accommodation  was  considered  and  men- 
tion made  of  the  fact  of  its  gradual  failure  from 
j^outh  to  age  with  an  accompanying  table  giving 
its  amplitude  at  various  ages.  The  individual  is 
unconscious  of  this  gradual  loss  of  accommodative 
power  until  it  becomes  so  reduced  as  to  make 
near  work  difficult  or  even  impossible. 

Since  the  great  portion  of  near  work  is  done 
at  about  13  inclies,  the  equivalent  of  approx- 
imately a  4-  S.50  D.  sphere  must  l)e  maintained 
to  focus  the  divergent  rays  originating  from  this 
nearby  source  of  illumination  on  the  retina  of  the 
emmetropic  eye  whether  it  occur  naturally  or  be 
by  lenses. 

Onset  of  Presbyopia:  A  glance  at  the  table 
referred  to  will  show  that  the  eye  usually  has 
just  this  amount  of  accommodative  power  at  the 
forty-fifth  year  and  that  it  is  gradually  reduced 
until  it  is  practically  absent  at  the  seventieth  year. 
Forty-five  then  is  said  to  be  the  age  of  the  onset 
of  presbyopia  because  it  is  at  that  time  that  the 
need  for  assisting  the  failing  accommodation  with 
stronger  and  stronger  convex  spheres  begins. 

Amount  of  Addition  Required:  In  de- 
termining the  strength  of  the  convex  spheres 
added,  the  eye  must  alwaj^s  be  considered  as 
emmetropic.  If  hypermetropic,  the  static  cor- 
rection must  be  added  to  that  given  for  age,  and, 
if  myopic,  must  be  deducted  from  it. 

Incidently,  it  should  be  noted  that  the  onset 
of  presbyopia  is  hastened  by  uncorrected  hyper- 
metropia;  that  it  is  delayed  by  myopia.    It  is  not 


PRESBYOPIA  183 

nature's  plan  to  ever  make  use  of  the  entire  quan- 
tity of  any  force  but  rather  to  hold  some  little  of 
it  in  reserve  for  emergencies.  For  this  reason  it 
is  found  advisable  to  supply  a  little  more  plus,  as 
we  say,  than  is  actually  required  for  the  usual 
working  distance.  This  gives  the  eye  a  small  re- 
serve for  occasional  near  work  and  makes  ])os- 
sible  a  greater  delicacy  of  adjustment  for  fine 
work.  The  following  table  gives  the  strength 
of  the  convex  lens  usually  required  at  different 
ages,  but  must  not  be  followed  exactly  because 
of  the  individual  variations  in  the  onset  of  de- 
gree of  presi)yopia  and  the  varying  working  dis- 
tance of  people  of  different  occupations. 

TABLE  FOR  PRESBYOPIC 
CORRECTION 

Age  Addition  required. 

45  1.  D.  Sphere. 

50  2.  D.  Sphere. 

55  2.50     Sphere. 

(W)  8.00     Sphere. 

Presbyopic  correction  of  Aphakic  Patients: 
Since  the  aphakic  patient  obviously  lias  no  ac- 
commodation A\'hatever,  he  may  quite  properly 
be  regarded  as  an  individual  of  seventy-five  years 
in  so  far  as  his  eyes  are  concerned,  and  be  given 
tlie  full  amount  of  near  correction  required  for 
the  working  distance  decided  u])on.  usually  three- 
and-one-half  dioptres. 


184    OPHTHALMOSCOPY,    RETINOSCOPY    AND    REFRACTION 

Xeak  Test  Type:  The  numbering  of  the 
Jaeger  type  described  in  the  previous  chapter 
lias  been  changed  in  recent  years  so  that  noting 
the  finest  type  the  patient  can  read  when  made 
emmetropic,  the  variously  sized  sections  are 
captioned  with  strength  of  the  plus  sphere  that 
likely  will  be  required  to  give  him  normal  near 
vision.  The  chart  like  the  table  must  be  con- 
sidered and  treated  individualh^,  seeking  to  give 
the  clearest  near  vision  with  the  greatest  range 
possible. 

Illustrated  Cases:  Case  XVIII — Mrs.  J. 
T.,  Aged  41.    Housewife. 

Complains  that  eyes  tire  at  near  work  for  last 
three  months;  has  never  worn  glasses  and  has 
recently  been  through  a  severe  illness. 

ExAMiXATiON  shows  her  to  be  emmetropic  but 
unable  to  read  the  finest  type  which  is  made  clear 
over  a  wide  range  with  a  +  .50  D.  sphere  before 
both  eyes. 

Given  above  for  near  work  only. 

Case  XV.    E.  B.,  Aged  50.    Farmer. 

Complains  of  inability  to  read  comfortably  for 
last  month.  Found  to  be  hypermetropic  one- 
half  dioptre  in  both  eyes  and  to  require  the  addi- 
tion of  a  +  .75  D.  sphere  before  both  eyes  to 
make  the  finest  type  clear.     Given: 

L.E. +  1.25  (^^'*  ^'^^''  ^''^^^' 


HETEROPHORIA — MUSCULAR    INSUFFICIENCY  ]  85 

C HAPTER  X 

HETEHOPJIORIA—MUSCl  LA R 
IXSVFFICIENCY 

Orthorplioria:    Pei-fect  binocular  balance. 

Ilctcrophoria:     Imperfect  binocular  balance. 

Esoplwna:  A  tendency  of  the  visual  axis  in- 
ward. 

Hyperesophoria:  A  tendency  of  the  visual 
axis  upward  and  inward. 

EiVophoria:  A  tendency  of  the  visual  axis  of 
one  eye  to  turn  out. 

Hypenwopliond:  A  tendency  of  the  visual 
axis  of  one  eye  to  be  above  the  other  and  outward. 

Hypophoria:  A  tendency  of  the  axis  of  one 
eye  to  be  below  the  other. 

Squint:  Cross  eye,  or  an  actual  deviation  of 
one  of  the  eyes  in,  out,  up  or  down. 

]Much  has  been  written  and  very  little  is  under- 
stood about  extrinsic  ocular  muscle  anomalies. 
]Many  theories  have  been  advanced  for  the  occur- 
rence and  correction  of  the  hetei"0])horia;  but  the 
fact  remains  that  they  often  disap]:)ear  sponta- 
neously on  wearino'  the  refractive  correction  and 
that  they  seldom  yield  to  treatment  by  means  of 
prism  exercises,  which  h()we\er,  should  be  tried 
before  resorting'  to  operative  ])rocedures. 

Diagnosis  of  Muscilak  Ekkors:  Tests  for 
muscular  anomalies  should  always  be  made  with 
the  patient  wearing-  the  refractive  correction  since 
very  often  there  is  much  less  insutficiencv  with 


186    OPHTHALMOSCOPY,    RETINOSCOPY    AND    REFRACTION 

the  lenses  than  there  is  when  they  are  not  worn. 
The  tests  all  depend  on  placing  the  muscular 
fusion  sense  in  abeyance  which  is  accomplished 
by  making  the  images  in  the  two  e3xs  so  different 
as  to  make  these  fusions  into  one  impossible. 

Various  accessories  have  been  developed  for 
this  purpose  but  none  are  better  than  the  Maddox 
Rod  before  one  eye  and  a  colored  disc  before  the 
other  when  the  patient  is  instructed  to  look  at 
a  small  light  at  a  distance  in  a  moderately 
darkened  room.  Under  these  conditions,  the  eye 
wearing  the  Maddox  Rod  sees  a  streak  of  light 
at  right  angles  to  the  direction  of  the  rod;  and 
the  other  one,  of  course,  sees  a  colored  light.  If 
they  coincide  the  eyes  are  in  a  state  of  muscular 
balance;  if  not,  the  strength  of  prism  placed  with 
bases  over  the  weaker  muscles  required  to  make 
tlie  images  coincide  is  the  measure  of  the  hetero- 
phoria.  Either  the  horizontal  or  vertical  muscles 
may  be  tested  by  simply  rotating  the  rod,  thus 
changing  the  direction  of  the  streak. 

In  addition  to  determining  the  static  condition 
by  the  above  method,  one  should  always  deter- 
mine the  measure  of  tlie  muscular  action  with 
the  fusion  sense  acting.  This  is  done  by  having 
the  patient  look  at  tlie  light  while  wearing  his 
correction  and  determining  the  strength  of  the 
prism  with  which  he  can  maintain  single  vision. 
Remember  that  the  apex  must  be  placed  o\  er  the 
muscle  tested.  The  normal  individual  should 
overcome  from  one  to  two  prism  dioptres  base 
up  or  down ;  four  to  six,  base  in ;  and  from  twelve 
to  eighteen  base  out. 


HETEROPHORIA  187 

Pkism  Tkka'I'mkxt  of  IIk'ikkoimiokia:  W'lieii 
a  heterophoria  does  not  disappear  on  wearing  the 
correction,  efforts  should  be  made  to  develop  the 
deficient  pair  of  muscles  by  means  of  appropriate 
prism  exercises.  In  using  prisms  to  exercise 
muscles,  one  must  remember  to  place  the  apex  of 
the  lens  over  the  muscle  to  be  exercised  and  to 
attempt  to  so  gauge  the  length  and  frequency  of 
treatment  and  increase  of  prism  as  to  stimulate 
the  muscle  rather  than  to  fatigue  it. 

Operative  Treatment  of  Heterophoria: 
Exophoria,  or  a  deviation  of  the  axis  outward  is 
the  usual  muscle  imbalance  requiring  operative 
treatment,  the  teclmique  of  which  is  the  same  as 
operations  for  squint  or  cross  eyes,  and  the  author 
believes  a  tenotomy  of  the  external  rectus  with 
a  retaining  suture  sliould  be  done,  but  not  imtil 
an  attempt  to  correct  tlie  refractive  error  has 
been  made. 


188    OPHTHALMOSCOPY,    RETINOSCOPY    AND    REFRACTION 

CHAPTER  X 

RETINOSCOPY 

Retinoscopy  is  a  method  of  estimating  the  re- 
fraction of  the  eye  by  studying  the  movements 
and  form  of  the  retinal  reflex  obtained  by  throw- 
ing a  beam  of  light  from  a  plane  mirror  into  the 
eye  from  a  given  distance. 

APPARATUS 

The  apparatus  necessary  for  this  ^vork  is  a 
plane  retinoscopic  mirror  of  about  one  and  one- 
half  inches  in  diameter,  a  good  light,  (preferably 
on  an  adjustable  bracket),  trial  frame  and  case 
of  trial  lenses.  As  to  the  light,  an  Argand  gas 
burner  or  an  electric  lamp,  spherical  in  shape 
and  frosted  to  prevent  an  image  of  the  filament 
showing,  are  the  best,  although  a  good  clear 
candle  or  oil  lamp  will  do. 

The  best  place  in  which  to  do  retinoscopy  is 
an  absolutely  dark  room,  but  an  outside  room 
with  the  windows  shaded  by  opaque  shades  an- 
swers all  purposes. 


RETINOSCOPY  189 

SCHEMATIC    EYE 

For  study  by  the  beginner, 
tlie  best  device  is  a  good  sclie- 
matic  eye  (Figure  4)  in  place 
of  the  patient,  as  it  does  not 
tire.  In  using  it,  the  iris  (h'a- 
])liragm  should  be  opened  or 
closed  until  the  pupillary  area 
is  the  size  of  a  weli  dilated 
pu])il,  or  about  one-fourth  of 
Fig.  180.   Retinoscope        .^j^  jj^^^jj  jj^  diamcter. 

arraxc;ement  of  the  light 

The  light  should  be  arranged  either  to  one  side 
of  the  patient's  head  on  a  level  with  the  ear,  or 
preferably  about  three  inches  above  the  patient's 
head.    The  face  should  always  be  in  a  shadow. 

POSITION  OF  OBSERVER 

The  observer  should  be  stationed  one  meter  in 
front  of  the  schematic  eye  or  patient  (Figure  32) 
as  this  is  the  farthest  one  can  work  w^ith  con- 
venience. The  eye  of  the  observer  and  that  of 
the  patient  should  be  on  a  level,  hence  it  is  con- 
venient to  have  a  screw  topped  stool  for  the 
observer,  and  a  stationary  to])ped  one  for  the 
patient,  a  (high  chair  with  back  and  arms  is  best 
for  children) . 

AVHAT  TO  LOOK  FOR 

Seated  one  meter  in  front  of  the  patient,  the 
mirror  held  in  the  right  or  left  hand,  as  is  easier 
for  him,  and  before  his  corresponding  eye,  the 


190    OPHTHALMOSCOPY,    RETINOSCOPY   AND    REFRACTION 

observer  catches  the  hght  from  the  lamp  and 
reflects  it  back  into  the  patient's  eye.  The  latter 
should  fix  a  point  midway  on  the  observer's  brow. 
If  strabismic,  the  unobserved  eye  should  be 
covered;  otherwise  the  patient  may  not  maintain 
fixation. 

When  the  observer  catclies  the  emergent  or  re- 
flected rays  on  his  own  retina,  lie  will  see  a  red 
reflex  in  the  patient's  pupil.  To  get  this  reflex- 
it  is  necessary  that  the  pupil  and  the  sight  hole 
of  the  mirror  coincide,  and  at  first  the  student 
may  have  to  close  the  eye  he  is  not  using,  but  he 
should  learn  to  keep  both  eyes  open. 

After  learning  to  see  the  retinal  reflex  the 
mirror  should  be  tilted  on  a  vertical  and  hori- 
zontal axis.  In  tilting  the  mirror  on  a  vertical 
axis  the  light  reflected  on  the  patient's  face  will 
move  in  the  same  direction  as  the  mirror  is  tilted 
or  in  the  vertical  meridian,  and  in  the  horizontal 
meridian  when  the  mirror  is  tilted  on  a  horizontal 
axis.  The  light  on  the  face  ahccu/s  moves  in  the 
same  direction  as  the  mirror  is  tilted — /.  e.  with 
the  mirror. 

The  reflex  in  the  pupillary  area  will  move  in 
different  directions,  presenting  different  appear- 
ances as  to  form,  brilliancy  and  rapidity  of 
movement  in  the  various  refractive  conditions  of 
the  eye. 

From  the  direction  of  movement,  we  learn  the 
following  facts,  viz:  if  the  reflex  moves  in  the 
same  direction  as  the  mirror  or  with  the  light  on 
the  face,  we  have  emmetropia,  hypermetropia,  or 
myopia  of  less  than  one  dioptre.     If  it  moves 


RETINOSCOPY  191 

against  the  mirror  or  opposite  the  hght  on  the 
face,  we  have  myopia  of  more  tlian  one  dioptre. 

The  ffwre  rapid  the 
movement  of  tlie  reflex, 
the  less  tlie  error;  and  the 
slower  the  movement,  the 

+3D         greater  the  error. 

The  viore  brilliant  the 
reflex,  the  less  the  error; 
and  the   dimmer  the  re- 

Fig.    181.      Specimen    retino-  n  i  i 

Ecopic  record  cross.     (Nu-         flex,  tile  ii'reater  the  error. 

gent.)  '  " 

The  form  or  shape  of 
the  reflex  in  simple  hypermetropia  and  myopia 
is  circnlar  or  crescentic  in  ontline,  and  in  the  as- 
tigmatic errors  it  is  elongated  or  there  is  a  distinct 
band  of  light  across  the  pupillary  area.  (See 
Pages  198-200.)  The  long  axis  of  tlie  band  is  in 
the  meridian  of  least  error. 

The  refracted  meridian  is  always  the  one  in 
^vhich  the  mirror  is  moved;  and  it  is  best  for  tlie 
beginner  to  refract  one  meridian  at  a  time,  as  he 
will  then  be  less  liable  to  get  confused  in  locating 
the  meridian  of  astigmatism  if  any.  In  making 
his  record,  it  is  convenient  to  make  a  diagram  of 
the  two  principal  meridians  in  the  form  of  a  cross, 
and  to  indicate  the  error  found  in  each  meridian. 
(Figure  181.) 

PRINCIPAL  MERIDIANS 

The  meridians  referred  to  in  refraction  are 
designated  on  the  graduated  arc  of  trial  frame 
(Figure  50)  and  corres])ond  to  the  meridians  as 


192    OPHTHALMOSCOPY,    RETINOSCOPY    AND    REFRACTION 

we  might  iinagiiit'  them  running  aeross  the  eornea 
and  numbered  on  its  circumference. 

While  in  all  circles  there  are  three  hundred  and 
sixty  degrees  (360  )  for  practical  purposes,  the 
trial  frame  is  graduated  in  divisions  of  five  de- 
grees (5°)  beginning  always  on  left  side  at  0° 
and  running  to  the  right  to  180°,  one-half  only 
of  the  circle  being  graduated.  Tlie  horizontal 
meridian  is  always  spoken  of  as  180°. 

When  the  radii  of  curvature  of  the  meridians 
are  all  equal,  the  error,  if  any,  is  spherical  (hy])er- 
metropia  or  myopia).  In  astigmatism,  there  is 
always  a  meridian  of  greatest,  and  one  of  least 
curvature  of  refraction.  These  meridians  are 
called  the  principal  meridians,  and  are  always 
90°  apart  in  regular  astigmatism. 

By  observing  the  point  on  the  trial  frame  where 
the  long  axis  of  the  band  of  light  strikes,  we  can 
judge  quite  readily  the  location  of  the  principal 
meridians,  as  the  long  axis  of  the  band  lies  in  the 
least  ametropic  meridian  and  the  other  is  90° 
from  it. 

We  often  note  an  oblique  movement  of  the 
reflex  across  the  pupillary  area  Avhen  we  move 
the  mirror  vertically  or  horizontally.  The  point 
on  the  trial  frame  where  the  line  in  which  the 
reflex  moves  strikes,  indicates  one  of  the  principal 
meridians;  the  other  is  90°  from  it.  While  this 
indicates  an  astigmatic  condition,  yet  we  cannot 
always  demonstrate  it  by  retinoscopy,  and  when 
an  astigmatism  is  found,  cylinders  are  not  always 
accepted  at  the  trial  case. 

Again,    where   they    are    accepted,    it   is    fre- 


RETINOSCOPY 


193 


FiK.    182 


Axonometer.      (Thor- 
ington.) 


queiitly  in  the  vertical  and  horizontal  merichans. 
A  more  accurate  way  to  locate  these  meridians  is 
to  use  the  axonometer  oF  Thorin<>ton.  (Figure 
18-2.) 

This  de\  ice  is  a  hlack 
disc  with  a  central 
apertui-e  the  si/e  oF  a 
dilated  ])n|)il  and  an 
arrow  ])oint  on  each 
side  oF  it.  It  is  placed 
in  the  trial  frame  and 
rotated  until  the  arrow 
points  coincide  with  tlie 
line  of  movement  of  tlie 
reflex,  of  the  long  axis 
of   the    hand    of   light, 

when  they  will  ])oint  to  one  of  the  i)rinci])al 
meridians  on  the  graduated  arc,  the  other  merid- 
ian heing  90°  from  this. 

THE  POIXT  OF  REVERSAL 

This  is  the  objective  point  aimed  at  in  retinos- 
copy.  It  is  the  point  in  front  of  the  eye  where 
emergent  rays  of  light  meet  or  cross,  and  at  this 
point  there  Avill  he  no  movement  of  the  reflex. 
We  establish  an  artificial  point  of  reversal  at 
which  we  aim  to  bring  emergent  rays  of  light  to 
a  meeting  ])oint  or  focus.  This  standard  ])oint  is 
one  meter,  and  as  long  as  emergent  rays  do  not 
cross  between  this  ])oint  and  the  patient's  eye, 
the  movement  of  tlie  light  reflex  is  with,  and  we 
must  place  plus  lenses  in  front  of  the  eye  until 


194    OPHTHALMOSCOPY,    RETINOSCOPY    AND    REFRACTIOy 

they  are  brought  to  a  focus  at  one  meter.  ( See 
Figs.  183  and  184.) 

If  on  the  other  hand  emergent  rays  of  hght 
cross  before  they  get  to  our  eye,  the  movement  oi 
the  reflex  Avill  be  against,  and  we  must  put  minus 
lenses  in  front  of  the  eye  until  they  are  brought 
to  a  focus,  at  one  meter.  ( See  Fig.  185. )  When 
this  point  is  found  there  will  be  no  movement  of 
the  light  reflex  in  the  pu])il.  This  is  the  ])oint 
of  reversal,  and  the  lens  bringing  the  rays  to  a 
focus  at  this  point  represents  the  refraction  of 
the  eye,  Avith  —  1  D.  added,  because  of  our  es- 
tablishing an  artificial  myopic  far  point  at  1 
meter;  or  practically,  we  have  rendered  the  eye 
1  D.  myopic  by  working  at  this  distance.  If  we 
w^orked  at  one-half  meter,  then  we  would  render 
the  eye  2  D.  myopic  and  would  add  —  2D. 

After  getting  the  foregoing  well  fixed  in  mind, 
the  student  should  practice  observing  the  reflex 
and  its  movement  in  the  schematic  eye  with  the- 
sliding  tube  in  different  positions. 

APPLICATION  OF  RETINOSCOPY 

For  accurate  retinoscopy,  the  accommodation 
of  the  patient's  eye  must  be  suspended.  This 
means  that  in  cases  where  asthenopia  is  marked 
cyclopegia  is  necessary.  When  asthenopia  is  not 
marked  or  wliere  accommodation  is  naturally  sus- 
pended simple  mydriasis  is  all  that  is  necessary 
and  this  is  only  for  the  purpose  of  getting  a  large 
enough  pupil  so  as  to  get  contrasting  light  and 
shadow. 


RETINOSCOPY 


195 


1  METER 
Fig.  183.     Emmetropia.      (Nugent.) 

EMMKTROPIA 

111  this  condition  we  will  find  the  reflex  moving 
with  the  mirror  and  plus  lenses  must  he  put  in 
front  of  tlie  eye  until  there  is  no  movement.  A 
+  1  D.  lens  will  give  u])  a  ])oint  of  no  movement, 
nnd  adding  our  —  1  D.  lens  for  the  one  meter 
distance,  we  have  0  or  emmetro])ia  as  the  result. 
(Fig.  188.) 


1  METER 

Fig.     184.     Hypermetropia.        (Nugent. 


HYPKRMETROPIA 

Here  again  we  will  find  the  reflex  moving 
with  the  mirror,  and  plus  lenses  must  he  placed 
in  front  of  the  eye  to  hring  the  rays  of  light  to 
a  focus  at  our  position  of  one  meter.  AMien  we 
have  the  plus  lens  that  gives  no  movement  of  the 
reflex,  we  have  estahlished  the  ])oint  of  reversal: 
and  if  we  aet  the  same  result  in  hotli  the  vertical 


196    OPHTHALMOSCOPY,    RETINOSCOPY   AND    REFRACTION 

and  horizontal  meridians,  we  have  a  simple  hy- 
permetropia. 

The  true  amount  of  error,  ho^vever,  ^vill  l)e 
represented  hy  tlie  strength  of  the  ])lus  lens 
found  with  — ^  1  D.  added,  i.  e.,  in  a  given  case  it 
takes  a  +  ^  I^-  to  give  the  point  of  reversal  in 
hoth  meridians,  adding  —  1  D.  the  result  is  -f-  8 
D.,  which  will  be  our  starting  point  at  the  trial 
case. 


1  METER 

Fig.    185.     Myopia.       (Nugent.) 


MYOPIA 

In  this  we  find  the  reflex  moving  with  the 
mirror  in  myopia  of  less  than  1  D.  because 
emergent  rays  cross  beyond  one  meter,  and  less 
than  +  1  D.  will  give  us  the  point  of  reversal. 
The  addition  of  —   1   D.  then  gives  less  than 

—  1  D.  as  the  resulting  myopia,  i.  e.,  +  ..50  I). 
gives  point  of  reversal  in  both  meridians,  adding 

—  1  D.,  the  result  is  —  ..50  D. 

In  myopia  of  more  than  1  D.  the  reflex  will 
alwaj^s  move  against  the  mirror,  and  we  must 
put  —  lenses  in  front  of  the  patient's  eye  to  bring 
the  rays  of  light  to  a  focus  at  one  meter.  The 
glass  which  gives  no  movement  of  the  reflex  es- 
tablishes the  point  of  reversal;  and  if  we  get  the 


RETINOSCOPY 


197 


same  result  in  both  the  vertical  and  horizontal 
meridians,  we  have  a  sim])le  mvo])ia.  (  Figure 
185.) 

The  true  amount  of  tlie  error,  however,  will  be 
represented  by  the  strength  of  the  —  lens  with 
—  1  D.  added,  i.  e.,  in  a  given  case  it  takes  a  — 
*i  D.  to  give  the  ])oint  of  reversal  in  both  merid- 
ians: adding  —  1  D.  the  result  is  —  4  D.  which 
will  be  our  starting  point  at  the  trial  case. 


APPLICATIOX  OF  KETIXOSCOPY 
ASTIGMATISM 

In  tliis  condition  we  will  find  the  reflex  assum- 
ing an  elongated  or  band  like  appearance  reach- 
ing across  the  pupillary  area,  the  long  axis  of  the 
elongated  reflex  or  band  being  in  the  meridian 
of  least  error  and  indicating  the  direction  in 
which  tlie  axis  of  the  correcting  cylinder  should 
be  i^laced. 

For  ])ractice  with  the  schematic 
eye,  an  astigmatism  can  be  pro- 
duced showing  tlie  band  of  liglit 
by  placing  a  cylinder  in  the  slot 
]jrovided  for  lenses  on  the  front 
end  of  tile  model.  Tlie  student 
must  remember  that  when  lie 
uses  a  plus  cylinder  he  is  ])ro- 
ducing  myopic  astigmatism,  and 
when  a  minus  cylinder,  hy])ermetropic  astig- 
matism. Cylinders  from  .7,5  D.  to  1..50  D.  give 
best  banded  reflect  wlien  used  on  a  scliematic  eve. 
(Figure  186.) 


Fig.    186.    Retinoscop- 

ic     illumination     and 

shadow     in     AstiRma- 

tism.      (May.) 


198    OPHTHALMOSCOPY,    RETli\OSCOPY    AND    REFRACTION 

SIMPLE   HYPERMETROPIC 
ASTIGMATISM 

The  reflex  will  move  with  in  hoth  meridians 
and  the  banded  appearance  will  be  seen  early. 
The  meridian  in  which  the  long  axis  lies  will  be 
corrected  with  a  +  1  I^-  lens,  indicating  em- 
metropia.  The  other  meridian  will  be  corrected 
with  a  stronger  -j-  lens  and  the  +  lens  giving 
the  point  for  that  meridian  Avith  —  1  D.  added 
will  indicate  the  amount  of  astigmatism.  (Figure 
187.)  This  result  will  be  the  starting  point  at 
the  trial  case,  i.  e.,  a  -)-  cylinder  with  the  axis  in 
the  emmetropic  meridian. 


+1D 


+2D 


Fig.    187.     Simple    Hypermetrcpic    Astigmatism.       (Nugent.) 

+  1.00  D.,  in  weak  meridian  +  2.00  D.  in 
strong  meridian,  adding  —  1.00  D.  will  give  0 
in  weaker  meridian,  indicating  emmetropia.  — 
1  D.  added  to  stronger  meridian  gives  +  1.00 
D.  which  requires  a  +  1-00  D.  cylinder  axis  90' 
or  in  weaker  meridian  indicated  by  the  band  of 
light. 


RETINOSCOPY 


199 


+  2D 


Fig.   188.     Compound   hypermetropic 
astigmatism    as    reflex    appears    be- 
fore    neutralizing     lenses     are    used. 
(Nugent.) 


+  3D 


Fig.    189.      Compound   hypermetropic 
astigmatism   as   reflex   appears   after 
the    weak    meridian    has    been    neu- 
tralized.      (Nugent.) 


COMPOUND  HYPERMETROPIC 
ASTIGMATISM  (Fig.  188  and  189) 
Here  the  reflex  moves  in  both  meridians,  but 
slower  in  one  than  in  the  other.  The  band  of 
light  may  not  appear  until  the  weaker  or  faster 
moving  meridian  is  corrected  or  nearly  so.  The 
result  will  be  a  stronger  tlian  +  1  D.  lens  in 
this  meridian,  and  a  stronger  one  still  for  the 
slower  moving  meridian,  i.  e.,  weak  meridian 
+  2  D.  strong  meridian  +  3  D.  adding  —  1  1). 
will  give  a  +  1  D.  for  the  weaker  and  a  +  1  D. 
sphere  with  a  +  1  1).  cylinder  with  its  axis  in 
the  weaker  meridian  or  +  1.00  +  1.00  ax  90^. 
(See  Xugent's  Rule.) 


Fig.   U 


Geneva   Ophthalmoscope   and   Retinoscope    (descriptive  pamphlet 
accompanies    the    instrument). 


200    OPHTHALMOSCOPY,    RETINOSCOPY   AND    REFRACTION 


+1.00 


FiK.    l'.*0.      Simple    Myopic    Astigma- 
tism  of  more  than   1    D.      (Nugent.) 


+1.50 


Fig.      191.        Simple     Hypermetropic 

Astigmatism     of     less     than     1     D. 

(Nugent.) 


SIMPLE   MYOPIC   ASTIGMATISM 

If  the  astigmatism  is  more  tlian  1  D.  we  Avill 
find  the  reflex  moving  with  the  mirror  in  one 
meridian  and  a  -f  1  D.  lens  will  give  the  point 
or  reversal;  adding  —  1  D.  gives  emmetropia 
for  that  meridian.  The  opposite  meridian,  how- 
ever, will  give  an  against  the  mirror  movement 
of  the  reflex  and  it  Avill  take  a  minus  lens  to  give 
the  point  of  reversal,  and  adding  a  —  1  D.  will 
give  one  more  dioptre  of  myopia  for  that  merid- 
ian. This  lens,  a  cylinder  with  tlie  axis  in  the 
emmetropic  meridian,  will  be  our  starting  point 
at  the  trial  case.  If  the  myopic  meridian  is  less 
than  1  D.  the  motion  of  the  reflex  will  be  with 
the  mirror;  the  point  of  reversal  will  be  indicated 
by  a  +  lens  of  less  than  1  D.  and  the  result  will 
be  estimated  the  same  as  in  myopia,  but  in  one 
meridian  at  a  time.     (Figure  191.) 


COMPOUND  MYOPIC  ASTIGMATISM 

If  the  myopia  is  more  than  1.00  D.  the  reflex 
will  move  against  the  mirror  in  both  meridians, 
but  at  different  rates.    The  more  rapidly  moving 


KTINOSCOPY 


201 


-2D 


I'i.LC.    1'.*:^.     Compound    myopic    astiK- 
matism    showinK    appearance    of    re- 
flex before  neulralizinR  lens  is  used. 
(Nugent.) 


-ID 


Fig.  193.  Compound  myopic  astig- 
matism showing  appearance  of  band 
of  light  after  meridian  of  least 
error  has  been  neutralized.  2  D 
Sph.  —  ID  cyl.  X  180.  See  Nu- 
gent's   Rule,    Paare  202. 


reflex  will  be  in  the  meridian  of  least  error  and  the 
more  slowly  moving  reflex  will  be  in  the  one  of 
greatest  error.  Estimating  each  meridian  sep- 
arately, and  adding  —  1  D.  for  our  distance  of  1 
meter,  as  in  all  other  cases,  we  have  as  a  result  a 
minus  sphere  combined  with  a  minus  cylinder 
with  its  axis  in  the  weaker  meridian.  Figures 
192  and  193. 

MIXED  ASTIGMATISM 

In  this  condition  we  will  find  the  two  meridians 
indicating  different  denominations  of  refraction, 
— ^i.  e.  myopia  in  one  and  hyperopia  in  the  other. 
Each  meridian  should  be  estimated  se])arately 
and  —  1  I),  be  added  to  the  correction  found 
for  each  meridian.  Figs.  184  and  185.  The  coi-- 
recting  lens  obtained  by  combining  the  two  lenses 
iiito  one  is  called  a  crossed  cylinder,  and  the  axes 
of  these  cylinders  are  90  apart  or  at  right  angles. 
Crossed  cylinder,  however,  is  not  often  used,  the 
correction  being  made  by  a  combination  of  a 
s])here  and  cylinder.     See  Xugent's  Kule. 


202    OPHTHALMOSCOPY,    RETINOSCOPY    AND    REFRACTION 

IRREGULAR  ASTIGMATISM 

Retinoscopy  does  not  give  very  satisfactory 
results  in  this  condition.  It  is  usually  caused  by 
opacities  on  the  cornea  or  lens,  and  these  so 
scatter  the  rays  of  light  that  no  distinct  direction 
of  movement  can  be  made  out.  However,  by 
persistence  a  result  may  be  obtained  which  is 
useful  as  a  foundation  in  getting  a  manifest  cor- 
rection that  will  be  beneficial  to  the  patient. 

LENSES  USED 

In  estimating  the  refraction  by  retinoscopy  the 
lenses  actually  necessary  are  spheres  only,  as  we 
estimate  first  one  meridian,  then  the  other.  Some 
refractionists,  however,  prefer  to  use  cylinders 
in  the  estimation  of  astigmatism.  This  is  un- 
necessary and  is  apt  to  be  confusing  because  of 
the  many  surfaces  for  reflections  of  light. 

Nugent's  Rule:  The  following  rule  devised 
by  Dr.  O.  B.  Xugent  for  the  purpose  of  writing 
formulae  from  net  retinoscopic  findings,  is  con- 
cise, accurate,  easy  to  understand  and  memorize, 
and  is  applicable  to  each  and  all  of  the  results 
obtained  by  the  retinoscope. 

The  Rule:  Choose  the  numeral  from  one 
(lesser)  meridian  for  the  sphere.  Xow  subtract 
this  number  from  the  numeral  in  the  other 
(greater)  meridian.  The  remainder  is  the 
strength  and  sign  of  the  cylinder,  the  axis  of 
which  is  indicated  by  the  meridian  from  which 
sph.  was  chosen.     (Figure  194.) 


RETINOSCOPY 


203 


+2 


sph. 

+2 


+2 

+2  no  cyl. 


+2 

+1 

sph. 

+  2 
+  1 

+  1= 

+  1x90 

-2 

+  1 

+2 

+2- 

-1  X  180 

-2 

sph. 

+3 
-2 

—^ 

2    +5x90 

+3 


-2 

+3 


+3       —5  x  180 
Fig.   194.     Nugent's  Rule 

PRACTICAL  WAY  OF  IIXDIXG  THE 
POIXT  OF  REVERSAL 

It  has  been  found  tliat,  as  the  point  of  no  move- 
ment of  the  refiex  is  hard  to  recognize  and  is 
generally  ambiguous,  the  most  practical  way  of 
finding  the  point  of  reversal  is  to  take  the  half- 
way point  between  the  strongest  lens  with  which 
the  reflex  distinctly  moves  in  the  same  direction 
and  the  weakest  lens  with  which  it  distinctly 
moves  in  the  opposite  direction,  i.  e.  in  a  given 
case  the  reflex  moves  without  a  lens,  and  tlie 
strongest  lens  with  which  it  moves  distinctly  with 
is  a  -r  4  13.,  the  weakest  with  which  it  moves  dis- 
tinctly against  is  a  +  4.. .50  D.,  or  the  half-way 


204    OPHTHALMOSCOPY,    RETINOSCOPY    AND    REFRACTION 

point  between  the  two  is  +  -4.25  D.,  or  the  point 
of  reversal.  Again,  if  the  reflex  without  lenses 
moves  against,  and  the  strongest  lense  with  wliich 
it  moves  against  is  a  —  5  D.,  and  the  weakest 
with  which  it  moves  with  is  a  —  5. 50  D.,  then 
the  half-way  point  between  them  is  —  .5.2.5  D.  or 
the  point  of  reversal. 

SPHERIC  ABERRATION 

This  is  a  condition  that  often  puzzles  the  be- 
ginner. Because  of  the  widely  dilated  pupil, 
there  are  two  distinct  areas  of  light  and  shadow, 
a  peripheral  one  and  a  central  one. 

In  positive  aberration  the  central  reflex  moves 
with,  and  the  peripheral  area  of  light  or  shadow, 
against  the  mirror. 

In  negative  aberration,  (conic  cornea)  the 
central  reflex  moves  against  and  the  peripheral 
one  with  the  mirror. 

If  the  student  will  get  in  the  habit  of  always 
observing  the  movement  of  the  reflex  throughout 
a  four  to  five  millimeter  area  at  the  apex  of 
the  cornea  he  will  not  be  bothered  by  these  con- 
ditions. We  do  not  care  for  the  refraction  in 
the  periphery  as  this  area  is  covered  by  the  iris, 
hence,  we  disregard  it. 

Spheric  aberration  is  frequently  annoying  in 
estimating  astigmatism  in  the  vertical  meridian. 
As  in  astigmatism  the  reflex  is  banded,  we  find 
in  this  condition  a  band  of  light  running  horizon- 
tally across  the  pupil,  with  the  ends  of  the  ring 
obliterated  by  the  iris.    This  gives  us  the  appear- 


RETINOSCOPY  205 

aiice  of  three  bands;  and  when  the  eye  is  tilted 
shghtly  np  or  down,  one  of  the  bands  is  not  seen, 
and  we  find  only  two  bands  which  come  together 
and  separate  like  the  blades  of  a  pair  of  scissors 
as  we  tilt  the  mirror  vertically.  The  condition 
is  called  the  scissors  movement,  and  is  sometimes 
ascribed  as  l)eing  due  to  a  tilting  of  the  lens  in 
its  fossa.  This  gives  another  reason  why  we 
should  stick  to  the  central  reflex.  The  lens  used 
to  correct  this  error  with  the  retinoscope  is  one 
that  will  keep  the  two  "bands  of  light"  together, 
or  nearly  so. 

VALUE  OF  RETIXOSCOPY 

The  value  of  retinoscopy  is  in  tiie  fact  that  it 
is  a  method  by  which  we  get  the  refraction  of 
the  eye  objectively.  This  makes  it  indispensable 
in  young  (Hypermetropic)  children,  with  stra- 
bismus or  other  condition  where  glasses  are  nec- 
essary, and  illiterates  from  any  cause,  who  cannot 
tell  us  wliat  lenses  they  see  best  witli  at  tlie  trial 
case. 

MVDKIATKS  AND  C  VC  LOPEGR'S 

For  many  cases  of  refraction,  the  use  of  drugs 
is  necessary  for  dilating  the  pupil  and  suspending 
the  accommodation  and  we  should  have  a  clear 
idea  in  our  minds  as  to  what  we  can  ex])ect  from 
those  drugs  and  how  to  use  them. 

A  mydriatic  is  a  drug  which  dilates  the  pupil. 

A  cyclo])egic  not  only  dilates  the  pu])il  but 
paralyzes  the  ciliary  muscle. 


206    OPHTHALMOSCOPY,    RETINOSCOPY   AND    REFRACTION 

All  cyclopegics  are  mydriatics,  but  all  my- 
driatics are  not  cyclopegics. 

The  following  table  gives  the  different  my- 
driatics and  cyclopegics  with  duration  of  the 
paralysis : 

Euphthalmin — purely  mydriatic. 

Cocoain — purely  mydriatic.  Occasionally 
slightly  cyclopegic. 

Homatropin — complete  ])aralysis — 2  liours ; 
complete  recovery  2  days. 

Scopolamin — complete  paralysis — ^o  hour; 
complete  recovery  4  days. 

Hyoscyamin — complete  ]jaralysis,  3  days; 
complete  recovery  8  days. 

Duboisin — complete  paralysis,  2  days;  com- 
plete recovery  8  days. 

Atropin — complete  paralysis,  2  days ;  complete 
recovery  1.5  days. 

Solution  of  proper  strength  of  those  drugs 
A\hen  dropped  into  the  eye,  in  a  short  time  begins 
to  give  effect,  by  acting  on  the  nerve  endings  of 
the  sphincter  muscles  of  the  iris  and  ciliary  body, 
paralyzing  their  action,  thus  producing  dilated 
pupil  and  suspension  of  accommodation. 

Atropin,  is  the  most  reliable  cyclopegic,  and 
where  accurate  suspension  of  accommodation  is 
desired  should  be  used.  It  is  used  in  solutions 
varying  from  two  to  ten  grains  to  the  ounce. 
The  two  grains  solution  for  children  up  to  the 
age  of  ten  years  and  the  four  grains  solution  from 
this  age  upward.  The  stronger  solution  is  gener- 
ally used  only  where  the  weaker  solution  has 
failed  to  give  complete  cyclopegia. 


RETINOSCOPY  207 

There  is  very  little  danger  of  getting  toxic 
effects  from  the  drug,  if  care  is  used  in  closing 
the  puncta  by  pressure  over  the  inner  canthi  with 
the  thumb  and  finger  dee])ly  enough  to  close  the 
canaliculi  and  instilling  the  solution  (not  drop- 
ping it)  into  the  eye  at  the  external  canthi.  In 
this  way  the  solution  is  kept  from  getting  into 
the  throat,  through  the  nasal  ducts,  swallowed, 
and  taken  up  by  the  stomach.  The  symptoms  of 
poisoning  are  dry  throat,  flushed  face,  and  rapid 
pulse,  and  when  they  occur  the  drug  should  be 
discontinued. 

The  action  of  this  drug  while  profound  is  slow, 
and  it  should  be  dropped  into  the  eyes  three 
or  four  times  a  day  for  three  days,  when  the 
cyclopegia  is  usually  complete,  and  the  patient 
ready  for  refraction.  If  the  cyclopegia  is  not 
complete,  it  can  be  used  for  a  day  or  two  longer. 
In  fact,  when  the  patient  is  using  atropine,  we 
might  as  well  use  it  long  enough  to  get  two 
examinations  approximating  each  other  pretty 
closely,  when  we  can  feel  certain  we  have  obtained 
the  best  result. 

Homatropin,  is  the  most  transient  cvclopegic 
we  have  and  is  very  useful  in  the  examination  of 
adults,  (and  even  good  results  can  be  secured  in 
children)  where  time  cannot  be  given  to  the  use 
of  atropin.  For  use  in  the  office  we  are  ac- 
customed to  use  the  Xo.  842  gelatin  disc  of 
Wyeth. 

It  is  used  also  in  2  per-cent  solution  in  water 
or  oil  (castor  or  olive)  one  drop  being  instilled 
into  the  conjunctival  sac  every  five  minutes  six 


208    OPHTHALMOSCOPY,    RETINOSCOPY    AND    REFKACTiON 

to  eight  times  when,  after  twenty  to  thirty 
minutes,  the  action  is  supposed  to  be  complete 
and  the  patient  ready  for  refraction. 

The  practical  way  to  use  the  discs  is  to  pick- 
up one  witli  a  pledget  of  cotton,  wound  on  a 
toothpick  or  probe  and, dampened  with  boric  acid 
solution  or  sterile  water,  and  ])lace  it  in  the  lower 
conjinictival  sac.  If  the  cotton  is  quite  wet  the 
disc  will  readily  adhere  to  the  conjunctiva.  Let 
the  patient  keep  his  eyes  closed  for  half  an  hour 
(best  by  bandaging),  use  a  separate  disc  in  each 
eye,  and  keep  the  eyes  closed  again;  action  will 
be  obtained  in  one  hour  from  the  time  first  disc 
is  used.  Some  ])refer  to  use  a  disc  every  twenty 
minutes  for  three  times,  Avaiting  twenty  minutes 
after  tlie  last  one  when  the  patient  is  ready  for 
refraction. 

Scopolamin  is  quite  a  favorite  with  some  ocu- 
lists, but  its  action  in  our  experience  is  no  better 
than  homatropin  and  the  effect  is  more  prolonged. 
It  is  advised  to  use  it  in  a  one  grain  to  the  ounce 
solution,  one  drop  of  which  solution  instilled  into 
the  conjunctival  sac  is  supposed  to  give  complete 
cyclopegia  in  one-half  hour. 

Hyoscyamin  is  not  often  used. 

Duboisin  is  useful  more  as  a  substitute  for 
atropin,  when  there  seems  to  be  an  idiosyncrasy 
for  the  latter  drug.  This  is  manifested  by  a 
marked  conjimctival  irritation  with"  erythema. 
Duboisin  is" best  used  in  a  1  per  cent  ointment. 


LENSES — PRESCRIPTIONS — FRAME   FITTING 


209 


CHAPTKK   XII 

.MKASIKKMKXT    OF    I.KXSKS,    PKK- 

SClill^TIOX   WlilTIXC;,  TKAXSPO- 

SITIOX  AXD  1  llA.^IK  1  Ti  TIXG 

The  determination  of  the  ])roper  correetion  is 
not  nearly  all  that  is  necessary  in  tlie  treatment 
of  refractive  errors;  hut,  if  success  in  this  im- 
portant branch  of  therapeutics  is  to  he  attained, 
as  much  care  must  he  taken  in  selecting  tlie  form 
of  lens  suited  to  the  case  and  in  ])roperly  mount- 
ing it  before  the  eye  as  is  used  in  doing  the  refrac- 
tion. 

Foinrs  of  Lkxses:  In  the  early  days  of  tlie 
s])ecialty,  s])]ierical  lenses  were  either  biconvex 
or  biconcave  as  tlie  case  might  be,  as  shown  iij 
Figures  19.5  and  196. 


Fig.   195.     Convex  Lenses.    1,  Piano- 
Convex  ;    2,    Bi-Convex  ;    3.    Convex 
Meniscus.      (May.) 


FiK.  lite.    Concave  Lenses.     1.  Plano- 
concave :     2,     Bi-Concave ;     3,     Con- 
cave Meniscus.      (May.) 


For  cosmetic  reasons  and  for  the  purpose  of 
bringing  the  periphery  of  the  lens  nearer  the 
eye  the  piano  convex  and  concave,  ( Figures  19,5 
and  196)  were  devised.  The  meniscus  form,  even 
with  only  the  usual  ])lus  or  minus  one  and  twenty- 


210    OPHTHALMOSCOPY,    RETINOSCOPY    AND    REFRACTION 

five  hundreths  D.  base  surface  has  been  found  so 
much  more  satisfactory  than  the  earlier  forms 
that  of  recent  years  much  deeper  meniscus  forms, 
six  dioptre  base  surface  or  even  in  some  cases 
nine  dioptre  base  surface  have  come  into  general 
use. 

This  form  has  been  found  to  be  comparatively 
free  from  annoying  reflections,  to  bring  the  edge 
of  the  lens  quite  near  the  eye  and  to  have  the 
added  advantage  of  causing  the  eye  to  look  more 
learly  at  right  angles  to  its  surface. 

ToRic  Lexs:  The  deep  meniscus  lens  has 
proven  so  satisfactory  that  there  has  been  de- 
veloped a  demand  for  a  similar  lens  in  cylindrical 
correction  which  has  been  met  by  the  toric  lens. 

By  varying  the  radii  of  curvature  any  desired 
difference  of  refractive  power  between  the  two 
meridians,  the  cylindrical  correction  may  be 
produced.  Then  by  grinding  a  neutralizing 
sphere  on  the  original  plane  surface,  the  spheri- 
cal correction  will  result. 

Example:  If  it  is  desired  to  make  a  +  1  D. 
sph.  C  -\-  1  cjd.  ax  90  in  the  toric  form,  a  blank 
is  selected  in  which  the  meridian  of  least  curva- 
ture, called  the  case  curve,  has  a  refractive  power 
of  6  D  and  the  stronger  one  has  the  refractive 
power  of  +  7  D.  Remembering  that  the  dioptric 
power  of  a  lens  is  equal  to  the  algebraic  sum  of 
the  two  surfaces  expressed  dioptrically,  we  now 
grind  a  minus  50  sphere  on  the  plane  surface  pro- 
ducing the  desired  strength,  and  cut  the  lens 
from  the  blank  with  its  weakest  meridian  at  90°. 


TRANSPOSITION    OF    LENSES  211 

Theoretically,  a  toric  lens  need  not  be  of  the 
deep  meniscns  form,  but  practically  they  always 
are  so,  because  the  sole  purpose  for  which  they 
are  made  is  to  obtain  the  advantat^es  resulting 
from  the  meniscus  form. 

Transposition  of  Lenses:  While  in  prac- 
tice, when  prescribing  toric  lenses,  it  is  safer  for 
the  oculist  to  leave  the  above  calculations  to  the 
optician;  it  is  necessary  that  he  have  a  thorough 
knowledge  of  transposition,  the  combining  of 
two  lenses  into  one  or  of  changing  the  form  of  a 
lens  to  a  more  desirable  one  while  retaining  the 
same  dioptric  power. 

RuEEs  FOR  Transposing:     Rule  1.    To  com- 
bine plus  spheres  and  cylinders  or  minus  spheres 
and  cylinders  to  produce  a  periscopic  lens,  take 
the  sum  of  the  sphere  and  cylinder  for  the  new 
sphere    and    retain    the    cylinder    with    its    sign 
changed  and  axis  moved  90  degrees. 
Examples:  1.   +  1  C  +  1  cyl.  ax.  10.5  =  +  2 
sph.  Z  —  1  ax.  1,5. 
2.-2  sph.  I  — -  .50  cyl.  ax.  180  — 
—  2.50  sph.  I  +  50  cyl.  ax.  90. 

Rule  2.     To  combine  spheres  and  cylinders  of 

opposite  signs,  take  their  numerical  difference  for 

the  new  sphere  giving  it  the  sign  of  the  stronger 

original  lens  and  retain  the  cylinder  changing  its 

sign  and  moving  its  axis  90  degrees. 

Examples:  1.  +  3  sph.  C  —  2  cyl.  ax.  90  = 

+  1  sph.  r_+  2  cyi.  ax.  180: 

2.   -f  .50  sph.  _  —  2.50  cyl.  ax.  150 

=  —  2  sph.  ^  +  2.50  cyl.  ax.  60 ; 


212    OPHTHALMOSCOPY,    RETINOSCOPY    AND    REFRACTION 

3.  —  8  sph.  r  +  3  cyl.  ax.  100  = 
+  2.00  sph.  _  —  1  cyl.  ax.  10; 

4.  —  1  sph.  Z  +  3  cyl.  ax.  100  =- 
+  2.00  sph.  Z  —3  cyl.  ax.  10. 

Rule  3.     To  convert  cylinders,  either  plus  or 
minus,  to  sphere  cylinders,  use  sphere  of  same 
power  and  sign  and  retain  cylinder  with  sign 
changed  and  axis  moved  90  degrees. 
Examples:  1.   +  2.25  cyl.  ax.  90  Z  +  2.25  sph. 
=  —  2.25  cvl.  ax.  180. 
2.  —  1.75  cvl.  ax.  180  Z  —  1.75  sph. 
=  +  1.75  cyl.  ax.  90. 
Rule  4.     To  change  crossed  cylinders  of  like 
sign  to  sphere  cylinders,  take  the  weaker  cylinder 
for  the  sphere  retaining  its  sign  and  the  differ- 
ence between  the  original  cylinders  for  the  new 
numerical  cylinders  retaining  the  sign  and  axis 
of  the  stronger. 

Examples:   1.   +  1  cyl.  ax.  lOJ)  1+2  cyl.  ax.  10 

=  +  1  sph.  I   +  1  cyl.  ax.  10; 

2.-2  cyl.  ax.  170  _  —  I'cyl.  ax.  80 

=  —  1  sph.  r  —  1  cyl.  ax.  170. 

or,  take  stronger  cylinder  for  sphere  retaining  its 

sign  and  the  numerical  difference  between  the 

original  cylinders  for  the  new  cylinder,  changing 

the  sign  and  giving  it  the  axis  of  the  stronger  one. 

Examples:   1.   +2.00  cyl.  ax.  180  I^+  3  cyl. 

ax.  90  ='+  3.00  sph.  Z  —  1  cyl. 

ax.  180; 

2.  —  3.00  cyl.  ax.  180  C  —  2  cyl. 

ax.  90  ='—  3.00  sph.  C  +  1  cyl. 

ax.  180. 

Rule  5.     To  change  crossed  cylinders  of  unlike 


TRANSPOSITION    OF    LENSES 


213 


sign  to  sphere-cylinders :  Take  either  cyhnder  for 
the  sphere  retaining  its  sign  and  the  algehraic 
sum  of  hoth  cylinders  for  the  new  cylinder  giving 
it  the  sign  and  axis  of  the  cylinder  not  nsed  for 
the  sphere. 
Examples:   1.   +  2  cyl.  ax.  90  I  —  1  cvl.  ax.  180 

=  +*^2.00  sph.    I   —.)i  cvl.  ax. 

180. 
2.  or  —  1  sph.  _  A-  3.00  cyl.  ax.  90. 
^Measurement  of  Patient's  Glasses  :  While 
it  is  perhaps  unwise  for  a  beginner  to  risk  the 
possibility  of  biasing  his  judgment  by  measuring 
the  glasses  the  patient  has  been  wearing  before 
completing  his  own  examination,  no  examination 
is  to  be  regarded  as 
complete  that  does 
not  c  o  n  t  a  i  n  a 
record  of  the  ])re- 
s  c  ri  ])  t  i  ()  n  he  is 


To  deter- 
mine  the  strength 
of  a  spectacle  lens, 
one  may  use  the 
general  lens  meas- 
ure (Bray ton  ])a- 
tent  Figure  197). 
which  gives  the  curvature  of 
instantlv  so  tliat  the  dioptric 


Measure 


the  two  surfaces 
strength  may  be 
found  by  a  simple  calculation,  or  their  strength 
may  be  determined  by  neutral i/ation  which  pro- 
cess all  operators  should  undei'stand. 


214    OPHTHALMOSCOPY,    RETINOSCOPY   AND    REFRACTION 

Neutralization  of  Lenses:  In  neutralizing 
a  lens,  the  first  step  is  to  determine  whether  it  is 
convex  or  concave  and  whether  or  not  it  contains 
a  cylinder  in  which  event  its  axis  must  be  located 
and  the  test  for  plus  and  minus  made  in  and  at 
right  angles  to  this  meridian. 

To  determine  whether  the  lens  is  convex  or 
concave,  if  its  curvature  is  not  so  great  as  to  make 
its  character  obvious,  look  through  it  at  a  distant 
object  which  will  be  observed  to  seem  to  move 
as  the  lens  is  moved  slightly  from  side  to  side. 
If  the  object  moves  opposite  the  direction  of 
lens  movement,  it  is  convex;  and  if  in  the  same 
direction,  it  is  concave.  Should  there  be  no  move- 
ment, it  must  be  a  piano. 

To  determine  the  presence  or  absence  of  a 
cylinder,  look  through  the  lens  at  some  object, 
preferably  a  line  that  cannot  be  seen  in  its  entirety 
while  looking  through  the  lens,  meanwhile,  slowly 
rotating  it.  If  the  line  remains  continuous  the 
lens  contains  no  cylinder;  but  if  the  line  becomes 
broken  diu-ing  the  rotation,  a  cylinder  is  present 
and  its  axis  lies  in  one  of  the  two  meridians  in 
which  the  line  was  not  broken. 

With  the  character  of  the  lens  determined,  it 
is  neutralized  by  placing  spheres  of  the  opposite 
sign  in  contact  with  it  and  repeating  the  move- 
ment test,  varying  strength  of  neutralization  lens 
until  there  is  noted  and  recorded  that  having  the 
strength  of  the  lens  under  examination,  using, 
of  course,  the  opposite  sign.  When  a  cylinder 
is  present  the  same  procedure  is  followed  save 
that  it  must  be  done  in  both  principal  meridians 


FRAME    FITTING  215 

obtaining  a  result  in  crossed  cylinders  which  may 

be  transposed  according  to  the  rules  just  given. 

FRAJVIE  FITTIXG:    Extreme  irnportance 

With  the  best  ])ossible  form  of  lenses  selected, 
they  must  be  mounted  accurately,  safely  and 
attractively  before  the  patient's  eyes.  The  choice 
between  the  eye  glasses  and  spectacles,  either  of 
which  may  be  rimless  or  in  frames,  may  usually 
be  left  to  the  patient  with  certain  reservations, 
save  in  the  case  of  young  children  who  invariably 
should  be  given  frame  spectacles. 

Choice  of  jNIounting:  If  the  ])atient  have 
no  astigmatism  and  so  desires  he  may  be  given 
regular  eye  glasses ;  but  if  he  has  an  astigmatism 
it  is  safer  for  him  to  wear  either  a  finger  piece 
mounting  or  spectacles,  since  the  regular  eye 
glasses  get  out  of  adjustment  readily  and  the 
cylinders  off  axis. 

Having  determined  on  the  form  in  which  the 
lenses  are  to  be  mounted,  the  next  step  is  to 
select  the  size  of  mounting  best  suited  to  the 
patient's  needs.  This  can  best  be  done  by  means 
of  fitting  sets  of  standard  sizes  of  bridges  which 
can  be  procured  in  either  eye  glasses,  (Figure 
198)  or  spectacles  (Figure  199)  from  any  whole- 
sale optician. 


216    OPHTHALMOSCOPY,    RETINOSCOPY    AND    REFRACTION 


Fig.    198.     Nose  Mountings 


Fig.    19i).     Spectacle  Fram 


I  N  T  E  R  P  U  P  I  T.- 

LARY  Distance  : 
We  !i  c)  w  deter- 
iiiiiie  t  li  e  inter- 
])U])illarv  distance 
by  actual  meas- 
urement, usually 
measuring  from 
the  inner  -margin 
of  one  ])upil  to 
to  the  outer  mar- 
gin of  the  other 
with  the  patient 
looking  at  the  dis- 
tance at  w  h  i  c  h 
the  glasses  are  to 
be  used. 


FRAME    FITTING  217 

III  ])ractice  tlic  ])atient  looks  over  the  o])erator\s 
head  for  (hstance  aiul  at  his  nose  for  near.  When 
measuring  the  inter-])ii])inarv  distance  one  shoidd 
rememher  too,  that  the  eyes  are  not  always  equi- 
distant from  the  mid  line,  and,  if  so.  order  his 
mounting  of  frame  accordingly. 

Selec'J'iox  of  Lenses:  With  the  individual 
mounting  selected  and  the  inter-pupillary  dis- 
tance known,  we  select  a  lens  of  such  size  and 
shape  (illustration  of  which  ma}'  he  found  in  any 
optical  catalogue)  as  will  place  their  o])tical  cen- 
ters exactly  hefore  the  pupils  and  at  the  same 
time  look  well  on  the  patient's  face.  If  there 
be  a  great  disparity  between  the  inter-pupillary 
distance  and  the  size  of  the  face  and  features, 
or  one  eye  be  farther  from  the  mid-line  than 
the  other,  decentering  of  one  or  both  lenses  may 
be  necessary. 

^NIeasukemext  fok  Spec'Tac'LEs:  When  order- 
ing spectacles,  in  addition  to  the  inter-pupillary 
distance,  one  must  determine  the  distance  between 
temples,  also  the  temple  length. 

Frame  Fitting  in  Pkesbyoi'ia:  Originally 
ametropic  i)resbyopic  patients  were  given  two 
])air  of  glasses:  but  at  present,  whenever  ])ossible, 
the  distant  and  near  coi-rection  are  placed  in  the 
same  mounting  in  some  form  of  bifocal.  Km- 
metro])ic  pi*esl)yo])es  also  frecjuently  object  to  the 
blurred  distant  vision  when  they  look  up  from 
near  work  and  aAoid  it  by  adding  their  presbyopia 
correction  to  a  ])lan()  for  distance.  Several  forms 
of  bifocals  have  been  devised,  the  efforts  for  im- 


218    OPHTHALMOSCOPY,    RETINOSCOPY    AND    REFRACTION 

provemeiits  being  directed  to  making  the  junc- 
tion of  the  near  and  distant  corection  invisible; 
but  the  one  point  that  must  be  remembered  is, 
with  the  main  portion  of  the  correcting  lens 
centered  for  distance,  to  have  the  reading  scales 
decentered  inward  two  millimeters. 

Adjustments:  With  the  greatest  possible 
care  in  frame  fitting  adjustments  Avill  be  found 
necessary  and  one  will  need  to  provide  himself 
with  suitable  pliers  and  learn  to  use  them.  A 
few  dollars  invested  in  a  supply  of  the  various 
mountings  and  spectacles  in  the  cheaper  grades 
and  time  spent  in  adjusting  them  to  different 
faces  will  well  repay  one  in  the  satisfaction  to 
his  patients  that  the  wearing  of  a  proper  correc- 
tion properly  mounted  always  brings. 


INDEX 

Page 

Aberration,  spheric 204 

Accommodation 93,  160 

Amplitude  of 161 

Acuity,  visual,  testing 129 

Amblyopia 105 

Aphakia 178 

Arteries,  retinal 15,  19 

Astigmatism: 

Causes 171 

Charts 131,  17(i 

Diagnosis  of 171.  177 

Forms  of 173 

Hypermetropic 181,  198,  199 

Irregular 202 

Mixed 177,  201 

Myopic 200 

Prevalence 175 

Regular 174 

Retinoscopy  in 197 

Symptoms 175 

Atrophic  spots  in  retina 16 

Atropin 158,  206 

Atrophy  of  oplic  nerve 33,  59.  61,  96 

Axonometer 1 93 

Blood,  pressure  of 1 05 

Blood,  vessels  of  retina 11.  19 

Campimeter 80 

Case,  trial 126 

Cataract 101 

Charts 127,  131,  176 

Choked  disc do 

Choroid : 

Coloboma 41 

Diseases 39 

Injuries 49 

Rings 15 

Rupture 49 

Sarcoma 41 

Choroiditis : 

Central 51 ,  53 

-Disseminated 47 

Posterior  staphyloma 45 

Conjugate  foci ;  .  .  .  119 

Cyclopegia  and  Cyclopegics 158,  159,  205 

Cylinders,  crossed 133 


Page 

Dioptre,  value  of -i 

Disc: 

Blank 125 

Choked 65 

Pinhole 125 

Placedo's 112 

Distance,  interpupillary 216 

Duboisin 206 

Embolism  of  Central  Artery  of  Retina 35 

Emmetropia 164.,  195 

Eserin 113 

Esophoria 185 

Examination  of  eye: 

With  opthalmoscope 97 

With  schematic  eye lU,  14 

Eupththalmin 206 

Eye,  direct  examination  with  ophthalmoscope 14,  97 

Fundus  of  human 14,  19,  90,  95,  104 

Injury  of,  by  fragment  of  steel 55 

Normal 11,  94 

Schematic,  examination  with 14 

Schematic,  for  ophthalmoscopic  study 7 

Exophoria 1 85 

Field,  glaucoma 79 

Haeminopsia 81 

Hysteria 81 

Normal 78 

Optic  atrophy 79 

Retrobulbar  neuritis 81 

Of  vision,  taking,  with  perimeter 77 

Of  vision,  taking,  without  perimeter 74 

Fisher's  lid  hooks 107 

Focus,  conjugate 119 

Of  lens 118 

Fogging  system 1 34 

Frame,  trial 1 23 

Frames,  lens,  fitting  of 215,  217 

Fundus,  of  human  eye 14,  19,  90,  95,  104 

Glaucoma 71,  110 

Hemorrhagic 73 

Vision  in 79 

Hemianopsia,  field  in 81 

Heterophoria 185,  187 

Homatropin,  use  (^f 158,  206 

Hooks,  lid,  Fisher's 107 

Hyoscyamin 206 

Hyperesophoria ]  85 

H^T>e^exophoria 185 

Hypermetropia 27,  166,  195 


1'age 

Hypophoria 185 

Hysteria — fielrl  of  vision  in 82 

Illiterate,  chart  for HT 

Illumination  for  ophthalmoscopy  ...  0 

Ol)li(|ue 84 

Images,  production  of  117 

Indicrs  of  refraction A'i'.i 

Injury,  by  fragment  of  steel  in  eye  o") 

Jaeger's  test  type 1'5" 

Kerato.scope 171 

Lachrymal  .sac 99.  10(1 

Lens,  action  of.  laws  1  Hi.  H"^ 

Test H;^ 

Lenses : 

Concave 1 1 H 

Convex 117 

('orrections  of  various  conditions  with H-2 

Cvlindrical HI.  H+ 

Foci  of 118 

Forms 209 

Material _ A'2i 

Measurement,  prescription  writing  -209.  ^17 

Meniscus "209 

Mounting 215 

Neutralization 214 

Selection  of 217 

Transposition 209 

Toric. 209 

Lid  hooks.  Fisher's 107 

Light,  for  opthalmoscopy 84 

Nature  and  j)roperties 110 

Refraction  of 1  H» 

Source  of 1 3,  84 

Lines,  white S9.  10* 

Maddox  rod ISC 

Measurement  of  len.ses 209.  -217 

Meridians,  principal 191 

Mountings,  for  lenses 215 

Mydriatics 205 

Muscular  insufficiencv 185 

Myopia ' 2.S.  1(59,  196 

Myopic  crescent 2:? 

Nerve,  field 42 

Optic  atrophy 59.  (51.  96 

Optic,  diseases  of 57 

Optic,  head  of 11.  19.  103 

Optic,  opaque  fibers 63 

Optic,  swollen 65.  67.  69 


Page 

Neuroretinitife 67 

Neuritis,  retrobulbar 81 

Xugent's  rule 202 

Oblique  illumination 84 

Ophthalmometer 172 

Ophthalmoscope : 

Electric 3 

Loring 3 

T'se  and  description  of 1 

Ophthalmoscopy,  direct 74,  86 

Indirect 84 

Optic  nerve,  atrophy 59,  61,  96 

Diseases  of 57 

Head  of 11,  19,  103 

Optical  principles 116 

Orthophoria 185 

Papillitis  hemorrhagica 69 

Paracentesis 115 

Perimeter 74 

Phorometer,  trial  frame 156 

Phoria : 

Prism  treatment  of 187 

Phoro-Optometer 154,  157 

Pigmented  spots 16 

Placedo's  disc 171 

Plus  tension Ill 

Position  in  eye  examination 13,  86 

Presbyopia 182 

Prisn^ 120 

Pupil,  occluded 114 

Distance  between 216 

Size  of 8 

Refraction,  applied 160 

Indices : 123 

Rules  for  correction  of 132 

Static  errors  of 122 

Refractor,  dvnamic 154 

Retina ' 11 

Atrophic  spots  in 16 

Blood  vessels 15,  19 

Detachment  of 27 

Diseases  of 25 

Embolism  of 35 

Light  streaks,  or  -white  lines 89,  102 

Red  reflex 102 

Vessels 11,  19 

Retinitis: 

Albuminuric 37 

Luetic 32 

Pigmentosa 31 


Retinoscopy 188 

Application  of 194 

Value  of 20.5 

Reversal,  point  of 193,  203 

Rings,  choroid 15 

Scleral 15 

Rule,  Nugent  \s 202 

Rules,  for  fogging 135 

For  hypermetropia 12 

For  mvopia 12 

For  refraction 132,  181 

For  retinoscopy 191 

For  taking  fields 92 

Schematic  eye 14 

Examination  of 10,  14 

Scleral  rings 15 

Scopolamin 206 

Scotoma,  central 76 

Screen,  with  schematic  eye 15 

Ski-Optometer 155 

Snellen's  test  types 127,  128 

Spectacles: 

Measurement  of 213 

Spectrum 119 

Spheric  aberration 204 

Spots,  atrophic 16 

Pigment 16 

Squint 1 85 

Staphyloma  with  Choroiditis 45 

Stenopic  slit 175 

Systemation  examination  of  eye 97 

Tension 112 

Causes  of Ill 

Plus Ill,  112 

Prognosis  of 112 

Treatment  of 1 12.  1 14 

Test  lens : ...]16 

Type 127,  130,  184 

Tonometer 108-109 

Transposition  of  lenses 209 

Trial  case 126 

Frame 123 

Type,  Jaeger's  test 130 

Near  test 18-4 

Vision : 

Acuity,  testing 129 

Taking  field  of 74,  77 

Visual  acuity 129 

Testing 129 


Model  "A":  a,  superior  turbinate;  b,  agger  nasi; 
c,  depression  above  c,  superior  meatus;  d,  middle 
turbinate;  e,  depression  above  e.  middle  meatus; 
f,  inferior  turbinate;  g,  depression  above  g,  in- 
ferior meatus;  h,  frontal  sinus;  i,  ethmoidal  cell; 
j,    eustachian    orifice;    k,    sphenoidal    sinus. 


Model  "B":  a,  a,  anterior  ethmoidal  cells;  b,  b,  b, 
posterior  ethmoidal  cells;  c,  sphenoidal  sinus;  d, 
superior  turbinate;  e,  depression  above  e,  recessus 
sphenoidalis;  f,  middle  turbinate;  g,  s])ace  above 
g,  middle  meatus  ;  h,  inferior  turbinate;  i,  inferior 
meatus;  j,  lacrimal  duct;  k,  depression  below  k, 
maxillaryostium;  1,  bulla  ethmoidalis;  m,  opening 
po^slerior  to  m,  ostium  of  bulla  ethmoidalis;  n,  de- 
pression below  n,  hiatus  semilunaris;  o,  ring  vicious 
circle;  p,  depression  posterior  to  p,  frontonasal 
duct;  q,  frontal  sinus;  r,  eustachian  orifice;  s, 
ridge   posterior  to   s,    processus   uncinatus. 


Internal 
Nose  Models 


W.  A.  Fisher,  M.D. 
Chicago 


F.A.C.S. 


It  is  (litiicult  1o  teach 
nasal  siirger}-  without  a 
good  understanding  of  the 
anatomy ,  and  the  subject 
is  not  an  ea.sy  one  to  teach 
from  drawings. 

The  models  are  sug- 
£^ested  to  replace  wet  spec- 
imens and  may  be  studied 
with  any  text  on  the  sub- 
ject. The}'  are  made  of 
rubber,  natural  in  size, 
[)ractically  indestructible, 
not  unsightly  and  can  be 
used  for  study  in  the  ph}-- 
sician's  office  or  for  dem- 
onstration in  the  operating 
room. 

For  the  general  practi- 
tioner and  rhinologist,  the 
models  are  suggested  as 
an  aid  in  diagnosis  and 
treating  focal  infections  of 
nasal  origin,  as  well  as 
laying  the  foundation  for 
nasal  surgery. 

Internal  Nose,  per  pair,  $5.00 
Postpaid  on  approval 

W.  A.  Fisher,  M.  D. 

31    N.   State   Street 
CHICAGO,  ILL.,  U.  S.  A. 


Dark   Normal   Fundus 

Plate  I, 


Light  Normal  Fundus 

Plate  II. 


Myopic  Crescent 

Plate  III. 


Detachment    of    Retina 

Plate  IV. 


Retinitis   Pigmentosa 

Plate  V. 


Retinitis  Pigmentosa  with  Oblong  Disc. 

Plate  VI. 


Opaque   Nerve   Fibn 

Plate  XIX. 


Plain    Choked    Disc 

Plate  XX. 


Neurorentinitis 

Plate  XXI. 


Pap::,:-:- 

Plate  XXII. 


Glaucoma 

Plate  XXIII. 


Plate  XXIV. 


Wi  /is her  - 

111  1 .  li  Opht  ha  Imo  s  c  opy , 

FF39o  retinoscopv  and 

1922  refraction. 


Biomedical 
Library 


A     000  386  660 


Biomedical 
Library 

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F5390 
1922 


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